feat(Notes): add favorite functionality to notes, allowing users to toggle favorites and filter notes accordingly

prisma/schema.prisma

@@ -146,6 +146,7 @@ model Note {
   taskId    String?  // Tâche associée à la note
   folderId  String?  // Dossier contenant la note
   order     Int      @default(0) // Ordre manuel de la note dans son dossier
+  isFavorite Boolean @default(false) // Note favorite
   createdAt DateTime @default(now())
   updatedAt DateTime @updatedAt
   user      User     @relation(fields: [userId], references: [id], onDelete: Cascade)