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/app/api/user/ai-consent/route.ts

@@ -0,0 +1,68 @@
+import { NextRequest, NextResponse } from 'next/server'
+import { auth } from '@/auth'
+import { prisma } from '@/lib/prisma'
+import { createHash } from 'crypto'
+
+/**
+ * POST /api/user/ai-consent
+ * Explicit AI Processing Consent — Logs explicit user consent for compliance.
+ * Optionally syncs consent state to UserAISettings if remember=true.
+ *
+ * Body: { consent: boolean, remember: boolean }
+ */
+export async function POST(req: NextRequest) {
+  try {
+    const session = await auth()
+    if (!session?.user?.id) {
+      return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
+    }
+
+    const userId = session.user.id
+
+    let body: { consent?: boolean; remember?: boolean } = {}
+    try {
+      body = await req.json()
+    } catch {
+      return NextResponse.json({ error: 'Invalid request body' }, { status: 400 })
+    }
+
+    const consent = body.consent ?? false
+    const remember = body.remember ?? false
+
+    // Get IP address and User-Agent
+    const ip = req.headers.get('x-forwarded-for') || '127.0.0.1'
+    const userAgent = req.headers.get('user-agent') || 'unknown'
+
+    // Hash/Anonymize IP address for strict GDPR compliance
+    const anonymizedIp = ip ? createHash('sha256').update(ip).digest('hex') : null
+
+    // Create persistent audit log of this consent decision
+    await prisma.aiConsentLog.create({
+      data: {
+        userId,
+        consent,
+        ipAddress: anonymizedIp,
+        userAgent,
+      },
+    })
+
+    // If remember is requested, persist state in UserAISettings
+    if (remember) {
+      await prisma.userAISettings.upsert({
+        where: { userId },
+        create: {
+          userId,
+          aiProcessingConsent: consent,
+        },
+        update: {
+          aiProcessingConsent: consent,
+        },
+      })
+    }
+
+    return NextResponse.json({ success: true })
+  } catch (error) {
+    console.error('[POST /api/user/ai-consent] failed:', error)
+    return NextResponse.json({ error: 'Internal Server Error' }, { status: 500 })
+  }
+}