feat(dashboard): tableau de bord Second Brain configurable avec chargement progressif

Briefing granulaire, pistes rapides puis enrichissement async, layout persisté v5,
suggestions agents, intégration Gmail et navigation sidebar alignée sur /home.

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

memento-note/app/actions/notes.ts

@@ -1082,6 +1082,27 @@ export async function getRecentNotes(limit: number = 3) {
   }
 }
 
+// Get count of unassigned notes (Inbox count) — notes without a notebook
+export async function getInboxCount() {
+  const session = await auth()
+  if (!session?.user?.id) return 0
+
+  try {
+    const count = await prisma.note.count({
+      where: {
+        userId: session.user.id,
+        notebookId: null,
+        isArchived: false,
+        trashedAt: null,
+      },
+    })
+    return count
+  } catch (error) {
+    console.error('Error counting inbox notes:', error)
+    return 0
+  }
+}
+
 // Dismiss a note from Recent section
 export async function dismissFromRecent(id: string) {
   const session = await auth();