feat: AI Overview recherche + AI Writer inline streaming

- AI Overview : synthèse IA en haut des résultats de recherche (Ctrl+K)
  - Service search-overview.service.ts
  - Endpoint /api/ai/search-overview
  - Carte 'Réponse IA' avec Sparkles en haut du panneau gauche
  - Pur additif, ne modifie pas le classement des résultats
- AI Writer inline : slash menu → 'Écrire avec l'IA' → champ inline
  - Mode 'write' dans paragraph-refactor.service.ts
  - Streaming paragraphe par paragraphe (120ms delay)
  - Nettoyage HTML (espaces vides supprimés)
  - Ref synchrone pour éviter fermeture du menu pendant la frappe
- Fix: index slashCommands AI Writer corrigé
- Fix: Loader2 import manquant
- i18n FR/EN

memento-note/components/search-modal.tsx

@@ -12,6 +12,8 @@ import {
   HelpCircle,
   Command,
   FileText,
+  Sparkles,
+  Loader2,
 } from 'lucide-react'
 import { useRouter } from 'next/navigation'
 import { useNotebooks } from '@/context/notebooks-context'
@@ -64,6 +66,8 @@ export function SearchModal({ isOpen, onClose }: SearchModalProps) {
   const [savedQueries, setSavedQueries] = useState<string[]>([])
   const [results, setResults] = useState<Note[]>([])
   const [isLoading, setIsLoading] = useState(false)
+  const [overview, setOverview] = useState<string | null>(null)
+  const [overviewLoading, setOverviewLoading] = useState(false)
   const [selectedIndex, setSelectedIndex] = useState(0)
 
   const inputRef = useRef<HTMLInputElement>(null)
@@ -137,6 +141,36 @@ export function SearchModal({ isOpen, onClose }: SearchModalProps) {
     }
   }, [query, searchInTrash])
 
+  // Fetch AI overview after results load
+  useEffect(() => {
+    if (!query.trim() || results.length === 0) {
+      setOverview(null)
+      return
+    }
+    setOverviewLoading(true)
+    const timer = setTimeout(async () => {
+      try {
+        const topResults = results.slice(0, 5).map(r => ({
+          title: r.title || 'Sans titre',
+          snippet: r.content?.replace(/<[^>]+>/g, ' ').replace(/\s+/g, ' ').trim().slice(0, 400) || '',
+        }))
+        const res = await fetch('/api/ai/search-overview', {
+          method: 'POST',
+          headers: { 'Content-Type': 'application/json' },
+          body: JSON.stringify({ query: query.trim(), results: topResults }),
+        })
+        const data = await res.json()
+        setOverview(data.hasRelevantInfo ? data.answer : null)
+      } catch {
+        setOverview(null)
+      } finally {
+        setOverviewLoading(false)
+      }
+    }, 500)
+
+    return () => clearTimeout(timer)
+  }, [query, results])
+
   // Reset selected index when results change
   useEffect(() => {
     setSelectedIndex(0)
@@ -501,6 +535,25 @@ export function SearchModal({ isOpen, onClose }: SearchModalProps) {
           {/* Left — results list */}
           <div className="w-[45%] h-full border-r border-border/40 dark:border-zinc-800 flex flex-col bg-[#FAF9F5]/30 dark:bg-[#121212]/30 overflow-hidden">
             <div className="flex-1 overflow-y-auto p-2 space-y-1">
+              {/* AI Overview */}
+              {(overviewLoading || overview) && (
+                <div className="mb-2 rounded-xl border border-brand-accent/20 bg-brand-accent/[0.03] p-3" dir="auto">
+                  <div className="flex items-center gap-1.5 mb-1.5">
+                    <Sparkles size={12} className="text-brand-accent" />
+                    <span className="text-[9px] font-bold uppercase tracking-widest text-brand-accent">
+                      {overviewLoading ? 'Analyse...' : 'Réponse IA'}
+                    </span>
+                  </div>
+                  {overviewLoading ? (
+                    <div className="flex items-center gap-2">
+                      <Loader2 size={12} className="animate-spin text-brand-accent" />
+                      <span className="text-[11px] text-muted-foreground">Synthèse des résultats...</span>
+                    </div>
+                  ) : (
+                    <p className="text-[12px] leading-relaxed text-foreground/80">{overview}</p>
+                  )}
+                </div>
+              )}
               {filteredMatches.map((m, idx) => {
                 const isSelected = idx === selectedIndex
                 return (