fix(audit): nettoyage accès, garde-fous build, unification quotas

Semaine 1 — fuites et accès :
- /archive rendu accessible via sidebar (était invisible)
- Suppression pages orphelines : /chat, /graph, /support, test-title-suggestions
- Fixes i18n : search-modal (clé non interpolée), sidebar tooltips, export PDF
- 15 locales mises à jour

Semaine 2 — garde-fous :
- 8 erreurs TS fixees → ignoreBuildErrors: false (build type-safe)
- reactStrictMode: true (dev-only, zero impact prod)
- reserveUsageOrThrow → wrapper deprecie vers reserveAiUsageOrThrow
- auth-guard.ts : requireAuthOrResponse() + requireAdminOrResponse()

Tests 212/212 | Lint 0 erreur | Build OK | tsc 0 erreur

memento-note/app/api/ai/suggest-notebook/route.ts

@@ -10,6 +10,7 @@ export async function POST(req: NextRequest) {
     if (!session?.user?.id) {
       return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
     }
+    const userId = session.user.id
 
     if (!(await hasUserAiConsent())) {
       return NextResponse.json({ error: 'ai_consent_required' }, { status: 403 })
@@ -32,11 +33,11 @@ export async function POST(req: NextRequest) {
     }
 
     const suggestedNotebook = await withAiQuota(
-      session.user.id,
+      userId,
       'auto_tag',
       () => notebookSuggestionService.suggestNotebook(
         noteContent,
-        session.user!.id,
+        userId,
         language
       ),
       { lane: 'tags' },