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/lib/dashboard/paths-fast.ts

@@ -0,0 +1,156 @@
+import type { DashboardPath } from '@/lib/dashboard/path-types'
+
+function excerpt(text: string, max = 120): string {
+  const plain = text.replace(/<[^>]+>/g, ' ').replace(/\s+/g, ' ').trim()
+  if (plain.length <= max) return plain
+  return `${plain.slice(0, max)}…`
+}
+
+export interface BriefingPathsInput {
+  recentNotes: Array<{
+    id: string
+    title: string | null
+    content: string
+    notebookId: string | null
+  }>
+  inboxCount: number
+  dueFlashcards: number
+  insights: Array<{
+    id: string
+    insight: string
+    score: number
+    viewed: boolean
+    note1: { id: string; title: string | null }
+    note2: { id: string; title: string | null }
+    note1Excerpt?: string
+    note2Excerpt?: string
+  }>
+  bridgeSuggestions: Array<{
+    clusterAId: number
+    clusterBId: number
+    clusterAName: string
+    clusterBName: string
+    suggestedTitle: string
+    suggestedContent: string
+    justification: string
+  }>
+  agentSuggestions: Array<{
+    id: string
+    topic: string
+    reason: string
+    clusterId: number | null
+  }>
+}
+
+/** Pistes instantanées à partir du briefing déjà chargé — sans requête lourde. */
+export function buildFastPathsFromBriefing(input: BriefingPathsInput): DashboardPath[] {
+  const paths: DashboardPath[] = []
+  const focus = input.recentNotes[0]
+
+  if (focus) {
+    paths.push({
+      id: `continue-${focus.id}`,
+      type: 'continue',
+      priority: 100,
+      title: focus.title || 'Untitled',
+      description: excerpt(focus.content, 140),
+      actionKey: 'continue',
+      noteId: focus.id,
+      notebookId: focus.notebookId ?? undefined,
+    })
+
+    for (const ins of input.insights
+      .filter(i => i.note1.id === focus.id || i.note2.id === focus.id)
+      .slice(0, 2)) {
+      const other = ins.note1.id === focus.id ? ins.note2 : ins.note1
+      paths.push({
+        id: `connect-${focus.id}-${other.id}`,
+        type: 'connect',
+        priority: 88,
+        title: other.title || 'Untitled',
+        description: ins.insight,
+        actionKey: 'compare',
+        noteId: focus.id,
+        note2Id: other.id,
+        notebookId: focus.notebookId ?? undefined,
+        score: Math.round(ins.score * 100),
+      })
+    }
+  }
+
+  const freshInsight = input.insights.find(i => !i.viewed)
+  if (freshInsight) {
+    paths.push({
+      id: `resurface-${freshInsight.id}`,
+      type: 'resurface',
+      priority: 85,
+      title: `${freshInsight.note1.title || '…'} ↔ ${freshInsight.note2.title || '…'}`,
+      description: freshInsight.insight,
+      actionKey: 'openInsight',
+      insightId: freshInsight.id,
+      noteId: freshInsight.note1.id,
+      note2Id: freshInsight.note2.id,
+      score: Math.round(freshInsight.score * 100),
+    })
+  }
+
+  for (const bridge of input.bridgeSuggestions.slice(0, 2)) {
+    paths.push({
+      id: `bridge-${bridge.clusterAId}-${bridge.clusterBId}`,
+      type: 'bridge',
+      priority: 70,
+      title: bridge.suggestedTitle,
+      description: bridge.justification || bridge.suggestedContent.slice(0, 140),
+      actionKey: 'createBridge',
+      clusterAId: bridge.clusterAId,
+      clusterBId: bridge.clusterBId,
+      notebookId: focus?.notebookId ?? undefined,
+    })
+  }
+
+  for (const agent of input.agentSuggestions.slice(0, 2)) {
+    paths.push({
+      id: `research-${agent.id}`,
+      type: 'research',
+      priority: 65,
+      title: agent.topic,
+      description: agent.reason,
+      actionKey: 'createAgent',
+      agentSuggestionId: agent.id,
+      notebookId: focus?.notebookId ?? undefined,
+    })
+  }
+
+  if (input.inboxCount > 0) {
+    paths.push({
+      id: 'organize-inbox',
+      type: 'organize',
+      priority: 60,
+      title: `${input.inboxCount} notes`,
+      description: 'inbox',
+      actionKey: 'organizeInbox',
+    })
+  }
+
+  if (input.dueFlashcards > 0) {
+    paths.push({
+      id: 'review-flashcards',
+      type: 'review',
+      priority: 55,
+      title: `${input.dueFlashcards}`,
+      description: 'flashcards',
+      actionKey: 'reviewCards',
+    })
+  }
+
+  paths.push({
+    id: 'daily-journal',
+    type: 'daily',
+    priority: 40,
+    title: new Date().toISOString().slice(0, 10),
+    description: 'daily',
+    actionKey: 'openDaily',
+  })
+
+  return paths.sort((a, b) => b.priority - a.priority).slice(0, 8)
+}