fix(api): correctly serialize user roles for database operations

User creation was failing with a JSON syntax error because the `roles` field (`List<String>`) was not being correctly serialized into a JSON array string for the database's `JSONB` column.

This change updates the `userRepository`'s configuration to use a custom `toJson` function. This function explicitly JSON-encodes the `roles` list before it's sent to the database client, resolving the error at the source without altering the generic repository or the User model.

Author: fulleni

lib/src/config/app_dependencies.dart

@@ -1,4 +1,5 @@
 import 'dart:async';
+import 'dart:convert';
 
 import 'package:ht_api/src/config/database_connection.dart';
 import 'package:ht_api/src/rbac/permission_service.dart';
@@ -124,7 +125,13 @@ class AppDependencies {
       connection,
       'users',
       User.fromJson,
-      (u) => u.toJson(),
+      (user) {
+        // The `roles` field is a List<String>, but the database expects a
+        // JSONB array. We must explicitly encode it.
+        final json = user.toJson();
+        json['roles'] = jsonEncode(json['roles']);
+        return json;
+      },
     );
     userAppSettingsRepository = _createRepository(
       connection,