test(gotrue): enable OAuth 2.1 server and fix response parsing

- Update GoTrue from v2.175.0 to v2.180.0
- Enable OAuth server with dynamic registration in test infrastructure
- Fix parsing of optional `aud` field in OAuthClientListResponse
- Handle empty response bodies (204 No Content) for delete operations
- Update delete test to expect null client on successful deletion

All OAuth admin endpoint tests now passing, matching behavior from
supabase/supabase-py#1240

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: grdsdev

infra/gotrue/docker-compose.yml

@@ -2,7 +2,7 @@
 version: '3'
 services:
   gotrue: # Signup enabled, autoconfirm on
-    image: supabase/auth:v2.175.0
+    image: supabase/auth:v2.180.0
     ports:
       - '9998:9998'
     environment:
@@ -29,6 +29,8 @@ services:
       GOTRUE_EXTERNAL_ANONYMOUS_USERS_ENABLED: 'true'
       GOTRUE_MFA_PHONE_ENROLL_ENABLED: 'true'
       GOTRUE_MFA_PHONE_VERIFY_ENABLED: 'true'
+      GOTRUE_OAUTH_SERVER_ENABLED: 'true'
+      GOTRUE_OAUTH_SERVER_ALLOW_DYNAMIC_REGISTRATION: 'true'
 
     depends_on:
       - db

packages/gotrue/lib/src/fetch.dart

@@ -199,7 +199,11 @@ class GotrueFetch {
     }
 
     try {
-      return json.decode(utf8.decode(response.bodyBytes));
+      final bodyString = utf8.decode(response.bodyBytes);
+      if (bodyString.isEmpty) {
+        return <String, dynamic>{};
+      }
+      return json.decode(bodyString);
     } catch (error) {
       throw _handleError(error);
     }

packages/gotrue/lib/src/gotrue_admin_oauth_api.dart

@@ -12,7 +12,7 @@ class OAuthClientResponse {
 
   factory OAuthClientResponse.fromJson(Map<String, dynamic> json) {
     return OAuthClientResponse(
-      client: OAuthClient.fromJson(json),
+      client: json.isEmpty ? null : OAuthClient.fromJson(json),
     );
   }
 }
@@ -21,19 +21,19 @@ class OAuthClientResponse {
 /// Only relevant when the OAuth 2.1 server is enabled in Supabase Auth.
 class OAuthClientListResponse {
   final List<OAuthClient> clients;
-  final String aud;
+  final String? aud;
 
   OAuthClientListResponse({
     required this.clients,
-    required this.aud,
+    this.aud,
   });
 
   factory OAuthClientListResponse.fromJson(Map<String, dynamic> json) {
     return OAuthClientListResponse(
       clients: (json['clients'] as List)
           .map((e) => OAuthClient.fromJson(e as Map<String, dynamic>))
           .toList(),
-      aud: json['aud'] as String,
+      aud: json['aud'] as String?,
     );
   }
 }

packages/gotrue/test/src/gotrue_admin_oauth_api_test.dart

@@ -62,7 +62,7 @@ void main() {
 
       final res = await client.admin.oauth.listClients();
       expect(res.clients, isNotEmpty);
-      expect(res.aud, isNotEmpty);
+      // aud is optional
     });
 
     test('get OAuth client by ID', () async {
@@ -105,9 +105,10 @@ void main() {
       final createRes = await client.admin.oauth.createClient(params);
       final clientId = createRes.client!.clientId;
 
+      // Delete returns 204 No Content with empty body
       final res = await client.admin.oauth.deleteClient(clientId);
-      expect(res.client, isNotNull);
-      expect(res.client?.clientId, clientId);
+      // The server returns 204 with no body, so client will be null
+      expect(res.client, isNull);
     });
   });