feat(dev_tools): add diagnostics hub with permissions audit tool

Evolve the platform-debug page into a diagnostics hub with sidebar
explorer layout. Add permissions audit API that introspects all
registered page routes and reports auth/permission enforcement status.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/modules/dev_tools/locales/fr.json

@@ -14,9 +14,20 @@
         "components": "Composants",
         "icons": "Icônes",
         "sql_query": "Requête SQL",
-        "platform_debug": "Debug Plateforme",
+        "diagnostics": "Diagnostics",
         "translation_editor": "Éditeur de traductions"
     },
+    "diagnostics": {
+        "title": "Diagnostics",
+        "platform_trace": "Trace Plateforme",
+        "permissions_audit": "Audit des Permissions",
+        "run_audit": "Lancer l'audit",
+        "status_ok": "OK",
+        "status_warning": "Avertissement",
+        "status_error": "Erreur",
+        "total_routes": "Routes totales",
+        "no_routes_match": "Aucune route ne correspond à vos filtres"
+    },
     "translation_editor": {
         "title": "Éditeur de traductions",
         "all_modules": "Tous les modules",