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/prisma/schema.prisma

@@ -191,6 +191,8 @@ model Note {
   incomingLinks              NoteLink[]               @relation("TargetLinks")
   clusterMemberships         ClusterMember[]
   bridgeNote                 BridgeNote?
+  sourceLiveBlocks           LiveBlockRef[]           @relation("SourceLiveBlocks")
+  targetLiveBlocks           LiveBlockRef[]           @relation("TargetLiveBlocks")
 
   @@index([isPinned])
   @@index([isArchived])
@@ -201,6 +203,19 @@ model Note {
   @@index([userId, notebookId])
 }
 
+model LiveBlockRef {
+  id             String   @id @default(cuid())
+  sourceNoteId   String
+  blockId        String
+  targetNoteId   String
+  createdAt      DateTime @default(now())
+  sourceNote     Note     @relation("SourceLiveBlocks", fields: [sourceNoteId], references: [id], onDelete: Cascade)
+  targetNote     Note     @relation("TargetLiveBlocks", fields: [targetNoteId], references: [id], onDelete: Cascade)
+
+  @@index([sourceNoteId, blockId])
+  @@index([targetNoteId])
+}
+
 model NoteHistory {
   id         String   @id @default(cuid())
   noteId     String