fix: organisateur IA — apply tag utilise syncNoteLabels au lieu de properties

- applyTag faisait un PATCH sur /api/notes/[id]/properties avec { tags: [...] }
  mais l'API properties attend { properties: { propId: value } }
- Maintenant: PATCH /api/ai/organize-notebook qui appelle syncNoteLabels()
- Les tags sont appliqués comme LABELS (système existant) sur les notes
- Merge avec labels existants (n'écrase pas)

memento-note/app/api/ai/organize-notebook/route.ts

@@ -3,6 +3,7 @@ import { auth } from '@/auth'
 import prisma from '@/lib/prisma'
 import { notebookOrganizerService } from '@/lib/ai/services/notebook-organizer.service'
 import { checkEntitlementOrThrow, QuotaExceededError, incrementUsageAsync } from '@/lib/entitlements'
+import { syncNoteLabels } from '@/app/actions/notes'
 
 export async function POST(request: NextRequest) {
   try {
@@ -55,3 +56,41 @@ export async function POST(request: NextRequest) {
     return NextResponse.json({ error: error.message || 'Failed to organize notebook' }, { status: 500 })
   }
 }
+
+export async function PATCH(request: NextRequest) {
+  try {
+    const session = await auth()
+    if (!session?.user?.id) {
+      return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
+    }
+
+    const { action, tagName, noteIds, notebookId } = await request.json()
+
+    if (action === 'apply_tag' && tagName && Array.isArray(noteIds)) {
+      // Fetch existing labels for each note, merge with new tag
+      for (const noteId of noteIds) {
+        const note = await prisma.note.findUnique({
+          where: { id: noteId },
+          select: { labels: true, notebookId: true },
+        })
+        if (!note) continue
+
+        let existingLabels: string[] = []
+        try { existingLabels = note.labels ? JSON.parse(note.labels) : [] } catch {}
+
+        if (!existingLabels.includes(tagName)) {
+          existingLabels.push(tagName)
+        }
+
+        await syncNoteLabels(noteId, existingLabels, note.notebookId, session.user.id)
+      }
+
+      return NextResponse.json({ success: true, applied: noteIds.length })
+    }
+
+    return NextResponse.json({ error: 'Invalid action' }, { status: 400 })
+  } catch (error: any) {
+    console.error('[Notebook Organizer PATCH] Error:', error)
+    return NextResponse.json({ error: error.message }, { status: 500 })
+  }
+}