fix: images, couverture, slash, agents, wizard, Stripe et admin

- Collage/accès images: ownership path userId + meta legacy, 403 non caché
- Couverture note: explicite (choix/aucune), plus d’auto depuis le corps
- Éditeur: suppression image TipTap, sync immédiate, toolbar réordonnée
- Slash: listes par titre (plus d’index), keywords nettoyés
- Agents: nextRun à la réactivation, cron sans stampede null
- Wizard: titres courts + mode Expert plus robuste
- Stripe checkout hosted fiable; admin métriques live; dark mode IA/settings
- Indexation notes courtes + test unit aligné

memento-note/app/actions/agent-actions.ts

@@ -240,10 +240,10 @@ export async function runAgent(id: string) {
     return { success: false, agentId: id, error: 'Agent introuvable' }
   }
 
-  // Fire and forget — return immediately so the UI doesn't block
-  import('@/lib/ai/services/agent-executor.service')
-    .then(({ executeAgent }) => executeAgent(id, userId))
-    .then(() => { /* revalidation is handled client-side via polling */ })
+  // Load module first so import failures surface immediately (not silently after response)
+  const { executeAgent } = await import('@/lib/ai/services/agent-executor.service')
+
+  void executeAgent(id, userId)
     .catch(err => console.error('[runAgent] Background error:', err))
 
   return { success: true, agentId: id, status: 'running' }
@@ -319,9 +319,35 @@ export async function toggleAgent(id: string, isEnabled: boolean) {
   }
 
   try {
+    const existing = await prisma.agent.findFirst({
+      where: { id, userId: session.user.id },
+      select: {
+        id: true,
+        frequency: true,
+        scheduledTime: true,
+        scheduledDay: true,
+        timezone: true,
+        nextRun: true,
+      },
+    })
+    if (!existing) throw new Error('Agent introuvable')
+
+    const data: { isEnabled: boolean; nextRun?: Date | null } = { isEnabled }
+
+    // When re-enabling a scheduled agent, ensure nextRun is set (was often null → never cron'd)
+    if (isEnabled && existing.frequency !== 'manual' && existing.frequency !== 'one-shot') {
+      const nextRun = calculateNextRun({
+        frequency: existing.frequency,
+        scheduledTime: existing.scheduledTime,
+        scheduledDay: existing.scheduledDay,
+        timezone: existing.timezone,
+      })
+      data.nextRun = nextRun
+    }
+
     const agent = await prisma.agent.update({
       where: { id, userId: session.user.id },
-      data: { isEnabled }
+      data,
     })
     return { success: true, agent }
   } catch (error) {