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/next.config.ts

@@ -5,10 +5,9 @@ const nextConfig: NextConfig = {
   output: 'standalone',
 
 
-  // Pre-existing TS errors in 3rd-party import paths (next/cache cookies, AI SDK v6 maxSteps)
-  // are false positives that don't affect runtime — skip type-check at build time
+  // Type-check at build time (TS errors block the build)
   typescript: {
-    ignoreBuildErrors: true,
+    ignoreBuildErrors: false,
   },
 
   // These server-side packages use Node.js internals (buffers, native modules, etc.)
@@ -77,9 +76,10 @@ const nextConfig: NextConfig = {
   // Hide the "compiling" indicator
   devIndicators: false,
 
-  // Disable strict mode: React 19 strict mode can cause double-invocation of render
-  // functions during concurrent transitions, amplifying timing issues.
-  reactStrictMode: false,
+  // React strict mode: double-invokes effects/renders in DEV ONLY (zero prod impact).
+  // Catches missing cleanups and side-effects in render. May surface pre-existing
+  // dev-mode issues that were hidden when this was disabled.
+  reactStrictMode: true,
 
   // Allow development origins for HMR and Dev Server access
   allowedDevOrigins: ['192.168.1.83'],