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/components/dashboard-widget-title-row.tsx

@@ -0,0 +1,37 @@
+'use client'
+
+import type { ReactNode } from 'react'
+import { DashboardWidgetHelp } from '@/components/dashboard-widget-help'
+import type { DashboardWidgetId } from '@/lib/dashboard/layout'
+
+interface DashboardWidgetTitleRowProps {
+  widgetId: DashboardWidgetId
+  icon?: ReactNode
+  title: string
+  actions?: ReactNode
+  className?: string
+}
+
+/** Titre widget : actions d’abord, aide « ? » en dernier — ne masque jamais la navigation. */
+export function DashboardWidgetTitleRow({
+  widgetId,
+  icon,
+  title,
+  actions,
+  className = 'mb-3',
+}: DashboardWidgetTitleRowProps) {
+  return (
+    <div className={`flex items-center justify-between gap-2 ${className}`}>
+      <div className="flex items-center gap-2 min-w-0 flex-1">
+        {icon}
+        <h2 className="text-[10px] font-mono font-bold uppercase tracking-widest text-ink dark:text-dark-ink truncate">
+          {title}
+        </h2>
+      </div>
+      <div className="flex items-center gap-1.5 shrink-0">
+        {actions}
+        <DashboardWidgetHelp widgetId={widgetId} />
+      </div>
+    </div>
+  )
+}