fix(api): provide model registry to root middleware

The generic data routes were failing with a "Bad state" error because the `ModelRegistryMap` was not being provided to the request context.

This change adds the `ModelRegistryMap` to the root middleware's dependency providers, making it available globally and resolving the error in the data route handlers.

Author: fulleni

routes/_middleware.dart

@@ -2,6 +2,7 @@ import 'package:dart_frog/dart_frog.dart';
 import 'package:ht_api/src/config/app_dependencies.dart';
 import 'package:ht_api/src/middlewares/error_handler.dart';
 import 'package:ht_api/src/rbac/permission_service.dart';
+import 'package:ht_api/src/registry/model_registry.dart';
 import 'package:ht_api/src/services/auth_service.dart';
 import 'package:ht_api/src/services/auth_token_service.dart';
 import 'package:ht_api/src/services/dashboard_summary_service.dart';
@@ -113,6 +114,7 @@ Handler middleware(Handler handler) {
       // 2. Provide all dependencies to the inner handler.
       final deps = AppDependencies.instance;
       return handler
+          .use(provider<ModelRegistryMap>((_) => modelRegistry))
           .use(provider<Uuid>((_) => const Uuid()))
           .use(provider<HtDataRepository<Headline>>((_) => deps.headlineRepository))
           .use(provider<HtDataRepository<Category>>((_) => deps.categoryRepository))