feat: Memento avec dates, Markdown, reminders et auth

Tests Playwright validés ✅:
- Création de notes: OK
- Modification titre: OK
- Modification contenu: OK
- Markdown éditable avec preview: OK

Fonctionnalités:
- date-fns: dates relatives sur cards
- react-markdown + remark-gfm
- Markdown avec toggle edit/preview
- Recherche améliorée (titre/contenu/labels/checkItems)
- Reminder recurrence/location (schema)
- NextAuth.js + User/Account/Session
- userId dans Note (optionnel)
- 4 migrations créées

Ready for production + auth integration

keep-notes/components/note-input.tsx

@@ -15,7 +15,9 @@ import {
   Archive, 
   MoreVertical,
   Undo2,
-  Redo2
+  Redo2,
+  FileText,
+  Eye
 } from 'lucide-react'
 import { createNote } from '@/app/actions/notes'
 import { CheckItem, NOTE_COLORS, NoteColor } from '@/lib/types'
@@ -34,6 +36,13 @@ import {
 } from '@/components/ui/dropdown-menu'
 import { cn } from '@/lib/utils'
 import { useToast } from '@/components/ui/toast'
+import { Dialog, DialogContent, DialogHeader, DialogTitle, DialogFooter } from '@/components/ui/dialog'
+import { MarkdownContent } from './markdown-content'
+
+interface HistoryState {
+  title: string
+  content: string
+}
 
 interface NoteState {
   title: string
@@ -56,6 +65,86 @@ export function NoteInput() {
   const [content, setContent] = useState('')
   const [checkItems, setCheckItems] = useState<CheckItem[]>([])
   const [images, setImages] = useState<string[]>([])
+  const [isMarkdown, setIsMarkdown] = useState(false)
+  const [showMarkdownPreview, setShowMarkdownPreview] = useState(false)
+  
+  // Undo/Redo history (title and content only)
+  const [history, setHistory] = useState<HistoryState[]>([{ title: '', content: '' }])
+  const [historyIndex, setHistoryIndex] = useState(0)
+  const isUndoingRef = useRef(false)
+  
+  // Reminder dialog
+  const [showReminderDialog, setShowReminderDialog] = useState(false)
+  const [reminderDate, setReminderDate] = useState('')
+  const [reminderTime, setReminderTime] = useState('')
+  const [currentReminder, setCurrentReminder] = useState<Date | null>(null)
+  
+  // Save to history after 1 second of inactivity
+  useEffect(() => {
+    if (isUndoingRef.current) {
+      isUndoingRef.current = false
+      return
+    }
+    
+    const timer = setTimeout(() => {
+      const currentState = { title, content }
+      const lastState = history[historyIndex]
+      
+      if (lastState.title !== title || lastState.content !== content) {
+        const newHistory = history.slice(0, historyIndex + 1)
+        newHistory.push(currentState)
+        
+        if (newHistory.length > 50) {
+          newHistory.shift()
+        } else {
+          setHistoryIndex(historyIndex + 1)
+        }
+        setHistory(newHistory)
+      }
+    }, 1000)
+    
+    return () => clearTimeout(timer)
+  }, [title, content, history, historyIndex])
+  
+  // Undo/Redo functions
+  const handleUndo = () => {
+    if (historyIndex > 0) {
+      isUndoingRef.current = true
+      const newIndex = historyIndex - 1
+      setHistoryIndex(newIndex)
+      setTitle(history[newIndex].title)
+      setContent(history[newIndex].content)
+    }
+  }
+  
+  const handleRedo = () => {
+    if (historyIndex < history.length - 1) {
+      isUndoingRef.current = true
+      const newIndex = historyIndex + 1
+      setHistoryIndex(newIndex)
+      setTitle(history[newIndex].title)
+      setContent(history[newIndex].content)
+    }
+  }
+  
+  // Keyboard shortcuts
+  useEffect(() => {
+    const handleKeyDown = (e: KeyboardEvent) => {
+      if (!isExpanded) return
+      
+      if ((e.ctrlKey || e.metaKey) && e.key === 'z' && !e.shiftKey) {
+        e.preventDefault()
+        handleUndo()
+      }
+      if ((e.ctrlKey || e.metaKey) && (e.key === 'y' || (e.key === 'z' && e.shiftKey))) {
+        e.preventDefault()
+        handleRedo()
+      }
+    }
+    
+    window.addEventListener('keydown', handleKeyDown)
+    return () => window.removeEventListener('keydown', handleKeyDown)
+  }, [isExpanded, historyIndex, history])
 
   const handleImageUpload = (e: React.ChangeEvent<HTMLInputElement>) => {
     const files = e.target.files
@@ -91,27 +180,37 @@ export function NoteInput() {
     e.target.value = ''
   }
 
-  const handleReminder = () => {
-    const reminderDate = prompt('Enter reminder date and time (e.g., 2026-01-10 14:30):')
-    if (!reminderDate) return
-
-    try {
-      const date = new Date(reminderDate)
-      if (isNaN(date.getTime())) {
-        addToast('Invalid date format. Use: YYYY-MM-DD HH:MM', 'error')
-        return
-      }
-
-      if (date < new Date()) {
-        addToast('Reminder date must be in the future', 'error')
-        return
-      }
-
-      // TODO: Store reminder in database
-      addToast(`Reminder set for: ${date.toLocaleString()}`, 'success')
-    } catch (error) {
-      addToast('Failed to set reminder', 'error')
+  const handleReminderOpen = () => {
+    const tomorrow = new Date(Date.now() + 86400000)
+    setReminderDate(tomorrow.toISOString().split('T')[0])
+    setReminderTime('09:00')
+    setShowReminderDialog(true)
+  }
+  
+  const handleReminderSave = () => {
+    if (!reminderDate || !reminderTime) {
+      addToast('Please enter date and time', 'warning')
+      return
     }
+    
+    const dateTimeString = `${reminderDate}T${reminderTime}`
+    const date = new Date(dateTimeString)
+    
+    if (isNaN(date.getTime())) {
+      addToast('Invalid date or time', 'error')
+      return
+    }
+    
+    if (date < new Date()) {
+      addToast('Reminder must be in the future', 'error')
+      return
+    }
+    
+    setCurrentReminder(date)
+    addToast(`Reminder set for ${date.toLocaleString()}`, 'success')
+    setShowReminderDialog(false)
+    setReminderDate('')
+    setReminderTime('')
   }
 
   const handleSubmit = async () => {
@@ -139,6 +238,8 @@ export function NoteInput() {
         color,
         isArchived,
         images: images.length > 0 ? images : undefined,
+        reminder: currentReminder,
+        isMarkdown,
       })
 
       // Reset form
@@ -146,10 +247,15 @@ export function NoteInput() {
       setContent('')
       setCheckItems([])
       setImages([])
+      setIsMarkdown(false)
+      setShowMarkdownPreview(false)
+      setHistory([{ title: '', content: '' }])
+      setHistoryIndex(0)
       setIsExpanded(false)
       setType('text')
       setColor('default')
       setIsArchived(false)
+      setCurrentReminder(null)
       
       addToast('Note created successfully', 'success')
     } catch (error) {
@@ -182,9 +288,12 @@ export function NoteInput() {
     setContent('')
     setCheckItems([])
     setImages([])
+    setHistory([{ title: '', content: '' }])
+    setHistoryIndex(0)
     setType('text')
     setColor('default')
     setIsArchived(false)
+    setCurrentReminder(null)
   }
 
   if (!isExpanded) {
@@ -217,6 +326,7 @@ export function NoteInput() {
   const colorClasses = NOTE_COLORS[color] || NOTE_COLORS.default
 
   return (
+    <>
     <Card className={cn(
       "p-4 max-w-2xl mx-auto mb-8 shadow-lg border",
       colorClasses.card
@@ -253,13 +363,46 @@ export function NoteInput() {
         )}
 
         {type === 'text' ? (
-          <Textarea
-            placeholder="Take a note..."
-            value={content}
-            onChange={(e) => setContent(e.target.value)}
-            className="border-0 focus-visible:ring-0 min-h-[100px] resize-none"
-            autoFocus
-          />
+          <div className="space-y-2">
+            {/* Markdown toggle button */}
+            {isMarkdown && (
+              <div className="flex justify-end gap-2">
+                <Button
+                  variant="ghost"
+                  size="sm"
+                  onClick={() => setShowMarkdownPreview(!showMarkdownPreview)}
+                  className="h-7 text-xs"
+                >
+                  {showMarkdownPreview ? (
+                    <>
+                      <FileText className="h-3 w-3 mr-1" />
+                      Edit
+                    </>
+                  ) : (
+                    <>
+                      <Eye className="h-3 w-3 mr-1" />
+                      Preview
+                    </>
+                  )}
+                </Button>
+              </div>
+            )}
+
+            {showMarkdownPreview && isMarkdown ? (
+              <MarkdownContent 
+                content={content || '*No content*'} 
+                className="min-h-[100px] p-3 rounded-md border border-gray-200 dark:border-gray-700 bg-gray-50 dark:bg-gray-900/50"
+              />
+            ) : (
+              <Textarea
+                placeholder={isMarkdown ? "Take a note... (Markdown supported)" : "Take a note..."}
+                value={content}
+                onChange={(e) => setContent(e.target.value)}
+                className="border-0 focus-visible:ring-0 min-h-[100px] resize-none"
+                autoFocus
+              />
+            )}
+          </div>
         ) : (
           <div className="space-y-2">
             {checkItems.map((item) => (
@@ -301,9 +444,12 @@ export function NoteInput() {
                   <Button 
                     variant="ghost" 
                     size="icon" 
-                    className="h-8 w-8" 
+                    className={cn(
+                      "h-8 w-8",
+                      currentReminder && "text-blue-600"
+                    )}
                     title="Remind me"
-                    onClick={handleReminder}
+                    onClick={handleReminderOpen}
                   >
                     <Bell className="h-4 w-4" />
                   </Button>
@@ -311,6 +457,27 @@ export function NoteInput() {
                 <TooltipContent>Remind me</TooltipContent>
               </Tooltip>
 
+              <Tooltip>
+                <TooltipTrigger asChild>
+                  <Button 
+                    variant="ghost" 
+                    size="icon" 
+                    className={cn(
+                      "h-8 w-8",
+                      isMarkdown && "text-blue-600"
+                    )}
+                    onClick={() => {
+                      setIsMarkdown(!isMarkdown)
+                      if (isMarkdown) setShowMarkdownPreview(false)
+                    }}
+                    title="Markdown"
+                  >
+                    <FileText className="h-4 w-4" />
+                  </Button>
+                </TooltipTrigger>
+                <TooltipContent>Markdown</TooltipContent>
+              </Tooltip>
+
               <Tooltip>
                 <TooltipTrigger asChild>
                   <Button 
@@ -390,31 +557,54 @@ export function NoteInput() {
                 </TooltipTrigger>
                 <TooltipContent>More</TooltipContent>
               </Tooltip>
-            </TooltipProvider>
 
-            <div className="flex gap-2">
-              <Button
-                onClick={handleSubmit}
-                disabled={isSubmitting}
-                size="sm"
-            </TooltipProvider>
+              <Tooltip>
+                <TooltipTrigger asChild>
+                  <Button 
+                    variant="ghost" 
+                    size="icon" 
+                    className="h-8 w-8" 
+                    onClick={handleUndo}
+                    disabled={historyIndex === 0}
+                  >
+                    <Undo2 className="h-4 w-4" />
+                  </Button>
+                </TooltipTrigger>
+                <TooltipContent>Undo (Ctrl+Z)</TooltipContent>
+              </Tooltip>
 
-            <div className="flex gap-2">
-              <Button
-                onClick={handleSubmit}
-                disabled={isSubmitting}
-                size="sm"
-              >
-                {isSubmitting ? 'Adding...' : 'Add'}
-              </Button>
-              <Button 
-                variant="ghost" 
-                onClick={handleClose}
-                size="sm"
-              >
-                Close
-              </Button>
+              <Tooltip>
+                <TooltipTrigger asChild>
+                  <Button 
+                    variant="ghost" 
+                    size="icon" 
+                    className="h-8 w-8" 
+                    onClick={handleRedo}
+                    disabled={historyIndex >= history.length - 1}
+                  >
+                    <Redo2 className="h-4 w-4" />
+                  </Button>
+                </TooltipTrigger>
+                <TooltipContent>Redo (Ctrl+Y)</TooltipContent>
+              </Tooltip>
             </div>
+          </TooltipProvider>
+
+          <div className="flex gap-2">
+            <Button
+              onClick={handleSubmit}
+              disabled={isSubmitting}
+              size="sm"
+            >
+              {isSubmitting ? 'Adding...' : 'Add'}
+            </Button>
+            <Button 
+              variant="ghost" 
+              onClick={handleClose}
+              size="sm"
+            >
+              Close
+            </Button>
           </div>
         </div>
       </div>
@@ -427,5 +617,48 @@ export function NoteInput() {
         onChange={handleImageUpload}
       />
     </Card>
+
+    <Dialog open={showReminderDialog} onOpenChange={setShowReminderDialog}>
+      <DialogContent>
+        <DialogHeader>
+          <DialogTitle>Set Reminder</DialogTitle>
+        </DialogHeader>
+        <div className="space-y-4 py-4">
+          <div className="space-y-2">
+            <label htmlFor="reminder-date" className="text-sm font-medium">
+              Date
+            </label>
+            <Input
+              id="reminder-date"
+              type="date"
+              value={reminderDate}
+              onChange={(e) => setReminderDate(e.target.value)}
+              className="w-full"
+            />
+          </div>
+          <div className="space-y-2">
+            <label htmlFor="reminder-time" className="text-sm font-medium">
+              Time
+            </label>
+            <Input
+              id="reminder-time"
+              type="time"
+              value={reminderTime}
+              onChange={(e) => setReminderTime(e.target.value)}
+              className="w-full"
+            />
+          </div>
+        </div>
+        <DialogFooter>
+          <Button variant="ghost" onClick={() => setShowReminderDialog(false)}>
+            Cancel
+          </Button>
+          <Button onClick={handleReminderSave}>
+            Set Reminder
+          </Button>
+        </DialogFooter>
+      </DialogContent>
+    </Dialog>
+  </>
   )
 }