feat: implement agent scheduled execution with cron and time picker

- Add scheduledTime, scheduledDay, timezone fields to Agent schema
- Create calculateNextRun() helper with timezone-aware scheduling
- Add POST /api/cron/agents endpoint for external scheduler
- Calculate nextRun on agent create, update, and after execution
- Add time/day picker in agent form (daily/weekly/monthly)
- Show "Next run" countdown in agent card
- Add i18n keys for schedule UI (FR + EN)

External scheduler (N8N, Vercel Cron) should call /api/cron/agents
every 5-15 min. Requires `prisma db push` to apply schema changes.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

memento-note/components/agents/agent-card.tsx

@@ -38,6 +38,7 @@ interface AgentCardProps {
     isEnabled: boolean
     frequency: string
     lastRun: string | Date | null
+    nextRun?: string | Date | null
     createdAt: string | Date
     updatedAt: string | Date
     _count: { actions: number }
@@ -196,6 +197,16 @@ export function AgentCard({ agent, onEdit, onRefresh, onToggle }: AgentCardProps
           <span>{t('agents.metadata.executions', { count: agent._count.actions })}</span>
         </div>
 
+        {agent.frequency !== 'manual' && agent.nextRun && (
+          <div className="flex items-center gap-1.5 text-xs text-muted-foreground mb-3">
+            <Clock className="w-3 h-3" />
+            {t('agents.schedule.nextRun')}{' '}
+            {mounted
+              ? formatDistanceToNow(new Date(agent.nextRun), { addSuffix: true, locale: dateLocale })
+              : new Date(agent.nextRun).toISOString().split('T')[0]}
+          </div>
+        )}
+
         {lastAction && (
           <div className={`
             flex items-center gap-1.5 text-xs px-2 py-1 rounded-md mb-3

memento-note/components/agents/agent-form.tsx

@@ -47,6 +47,9 @@ interface AgentFormProps {
     maxSteps?: number
     notifyEmail?: boolean
     includeImages?: boolean
+    scheduledTime?: string | null
+    scheduledDay?: number | null
+    timezone?: string | null
   } | null
   notebooks: { id: string; name: string; icon?: string | null }[]
   onSave: (data: FormData) => Promise<void>
@@ -88,6 +91,11 @@ export function AgentForm({ agent, notebooks, onSave, onCancel }: AgentFormProps
   const [sourceNotebookId, setSourceNotebookId] = useState(agent?.sourceNotebookId || '')
   const [targetNotebookId, setTargetNotebookId] = useState(agent?.targetNotebookId || '')
   const [frequency, setFrequency] = useState(agent?.frequency || 'manual')
+  const [scheduledTime, setScheduledTime] = useState(agent?.scheduledTime || '08:00')
+  const [scheduledDay, setScheduledDay] = useState<number>(agent?.scheduledDay ?? 1)
+  const [timezone] = useState(() => {
+    try { return Intl.DateTimeFormat().resolvedOptions().timeZone } catch { return 'UTC' }
+  })
   const [selectedTools, setSelectedTools] = useState<string[]>(() => {
     if (agent?.tools) {
       try {
@@ -177,6 +185,9 @@ export function AgentForm({ agent, notebooks, onSave, onCancel }: AgentFormProps
       formData.set('maxSteps', String(maxSteps))
       formData.set('notifyEmail', String(notifyEmail))
       formData.set('includeImages', String(includeImages))
+      formData.set('scheduledTime', scheduledTime)
+      formData.set('scheduledDay', String(scheduledDay))
+      formData.set('timezone', timezone)
 
       await onSave(formData)
     } catch {
@@ -356,6 +367,59 @@ export function AgentForm({ agent, notebooks, onSave, onCancel }: AgentFormProps
             </select>
           </div>
 
+          {/* Schedule config: time + day pickers (hidden for manual/hourly) */}
+          {frequency !== 'manual' && frequency !== 'hourly' && (
+            <div className="flex gap-3">
+              {/* Day selector (weekly/monthly only) */}
+              {frequency === 'weekly' && (
+                <div className="flex-1">
+                  <label className={labelCls}>{t('agents.schedule.dayOfWeek')}</label>
+                  <select
+                    value={scheduledDay}
+                    onChange={e => setScheduledDay(Number(e.target.value))}
+                    className={selectCls}
+                  >
+                    {[
+                      { value: 0, label: t('agents.schedule.days.mon') },
+                      { value: 1, label: t('agents.schedule.days.tue') },
+                      { value: 2, label: t('agents.schedule.days.wed') },
+                      { value: 3, label: t('agents.schedule.days.thu') },
+                      { value: 4, label: t('agents.schedule.days.fri') },
+                      { value: 5, label: t('agents.schedule.days.sat') },
+                      { value: 6, label: t('agents.schedule.days.sun') },
+                    ].map(d => (
+                      <option key={d.value} value={d.value}>{d.label}</option>
+                    ))}
+                  </select>
+                </div>
+              )}
+              {frequency === 'monthly' && (
+                <div className="flex-1">
+                  <label className={labelCls}>{t('agents.schedule.dayOfMonth')}</label>
+                  <select
+                    value={scheduledDay}
+                    onChange={e => setScheduledDay(Number(e.target.value))}
+                    className={selectCls}
+                  >
+                    {Array.from({ length: 31 }, (_, i) => i + 1).map(d => (
+                      <option key={d} value={d}>{d}</option>
+                    ))}
+                  </select>
+                </div>
+              )}
+              {/* Time picker */}
+              <div className="flex-1">
+                <label className={labelCls}>{t('agents.schedule.time')}</label>
+                <input
+                  type="time"
+                  value={scheduledTime}
+                  onChange={e => setScheduledTime(e.target.value)}
+                  className={inputCls}
+                />
+              </div>
+            </div>
+          )}
+
           {/* Email Notification */}
           <div
             onClick={() => setNotifyEmail(!notifyEmail)}