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/components/sidebar.tsx

@@ -1536,6 +1536,22 @@ export function Sidebar({ className, user }: { className?: string; user?: any })
               </span>
             </Link>
 
+            <Link
+              href="/archive"
+              className={cn(
+                'w-9 h-9 rounded-lg flex items-center justify-center transition-all relative group',
+                pathname === '/archive'
+                  ? 'bg-amber-500/10 text-amber-500 border border-amber-500/25'
+                  : 'text-concrete hover:text-amber-500 hover:bg-amber-500/5'
+              )}
+            >
+              {pathname === '/archive' && <div className="absolute left-0 top-1/2 -translate-y-1/2 w-[3px] h-4 bg-amber-500 rounded-r-full" />}
+              <Archive size={16} />
+              <span className="absolute left-[50px] top-1/2 -translate-y-1/2 bg-ink dark:bg-white dark:text-ink text-paper text-[9px] font-bold py-1 px-2 rounded opacity-0 group-hover:opacity-100 transition-opacity whitespace-nowrap z-50 pointer-events-none shadow-md uppercase tracking-wider">
+                {t('sidebar.archive')}
+              </span>
+            </Link>
+
             <Link
               href="/home?shared=1&forceList=1"
               className={cn(
@@ -1558,7 +1574,7 @@ export function Sidebar({ className, user }: { className?: string; user?: any })
             >
               <Search size={15} />
               <span className="absolute left-[50px] top-1/2 -translate-y-1/2 bg-ink dark:bg-white dark:text-ink text-paper text-[9px] font-bold py-1 px-2 rounded opacity-0 group-hover:opacity-100 transition-opacity whitespace-nowrap z-50 pointer-events-none shadow-md uppercase tracking-wider">
-                Recherche (Ctrl+K)
+                {t('sidebar.searchShortcut')}
               </span>
             </button>
 
@@ -1568,7 +1584,7 @@ export function Sidebar({ className, user }: { className?: string; user?: any })
             >
               {isDark ? <Sun size={15} /> : <Moon size={15} />}
               <span className="absolute left-[50px] top-1/2 -translate-y-1/2 bg-ink dark:bg-white dark:text-ink text-paper text-[9px] font-bold py-1 px-2 rounded opacity-0 group-hover:opacity-100 transition-opacity whitespace-nowrap z-50 pointer-events-none shadow-md uppercase tracking-wider">
-                {isDark ? 'Mode clair' : 'Mode sombre'}
+                {isDark ? t('sidebar.lightMode') : t('sidebar.darkMode')}
               </span>
             </button>