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/api/cron/gmail/route.ts

@@ -0,0 +1,49 @@
+import { NextRequest, NextResponse } from 'next/server'
+import prisma from '@/lib/prisma'
+import { gmailScannerService } from '@/lib/integrations/gmail-scanner.service'
+
+export const dynamic = 'force-dynamic'
+
+function authorize(request: NextRequest): boolean {
+  const cronSecret = process.env.CRON_SECRET
+  if (!cronSecret) return false
+  const authHeader = request.headers.get('authorization')
+  const bearer = authHeader?.startsWith('Bearer ') ? authHeader.slice(7) : null
+  return bearer === cronSecret
+}
+
+/** POST /api/cron/gmail — scan Gmail for connected users (1×/jour en prod via entrypoint) */
+export async function POST(request: NextRequest) {
+  if (!authorize(request)) {
+    return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
+  }
+
+  const users = await prisma.userAISettings.findMany({
+    select: { userId: true, integrationTokens: true },
+    take: 200,
+  })
+
+  const connected = users.filter(u => {
+    if (!u.integrationTokens) return false
+    try {
+      const meta = typeof u.integrationTokens === 'string'
+        ? JSON.parse(u.integrationTokens)
+        : u.integrationTokens
+      return !!(meta?.gmailAccessToken && meta?.gmailRefreshToken)
+    } catch {
+      return false
+    }
+  })
+
+  let totalCreated = 0
+  for (const row of connected) {
+    try {
+      const { created } = await gmailScannerService.scanUser(row.userId)
+      totalCreated += created
+    } catch (err) {
+      console.error('[CronGmail]', row.userId, err)
+    }
+  }
+
+  return NextResponse.json({ success: true, users: connected.length, notesCreated: totalCreated })
+}