feat(notes): liens internes, onglet Réseau, living blocks et consentement IA

Rend les liens entre notes visibles et persistants (sync NoteLink au save, auto-save, graphe réseau rafraîchi), ajoute living blocks, Memory Echo, recherche globale, consentement IA explicite et consolide les prototypes design en architectural-grid.

Co-authored-by: Cursor <cursoragent@cursor.com>

memento-note/lib/ai/services/memory-echo.service.ts

@@ -96,6 +96,16 @@ export class MemoryEchoService {
    * Find meaningful connections between user's notes
    */
   async findConnections(userId: string, demoMode: boolean = false): Promise<NoteConnection[]> {
+    // GDPR AI Consent check — compliance skip if not granted (AC6)
+    const userSettings = await prisma.userAISettings.findUnique({
+      where: { userId },
+      select: { aiProcessingConsent: true },
+    })
+    if (!userSettings?.aiProcessingConsent) {
+      console.log(`[MemoryEchoService] User ${userId} has not given AI consent. Skipping connection generation for compliance.`)
+      return []
+    }
+
     // Ensure all notes have embeddings before searching for connections
     await this.ensureEmbeddings(userId)