fix(ci): fix integration test collection and skip Playwright in CI

- Add @pytest.mark.oauth to OAuth-dependent tests in
  test_scope_authorization.py so they're excluded from single-user job
- Add module-level pytestmark to test_introspection_authorization.py
- Fix single-user marker expression to also exclude oauth smoke tests
- Add --ignore paths for multi-user, qdrant, and RAG evaluation tests
- Uncomment GITHUB_ACTIONS skip in oauth_callback_server fixture
- Add GITHUB_ACTIONS skip to login_flow_oauth_token fixture
- Mount third_party/oidc volume in docker-compose.yml app service
- Add OIDC diagnostic step in CI for playwright jobs

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

tests/server/oauth/test_introspection_authorization.py

@@ -27,6 +27,8 @@ from ...conftest import _handle_oauth_consent_screen
 
 logger = logging.getLogger(__name__)
 
+pytestmark = [pytest.mark.integration, pytest.mark.oauth]
+
 
 @pytest.fixture(scope="module")
 def nextcloud_host() -> str:
@@ -114,7 +116,6 @@ async def test_oauth_clients(
     logger.info("Test OAuth clients fixture complete")
 
 
-@pytest.mark.integration
 async def test_introspection_requires_client_authentication(
     oidc_endpoints: dict[str, str],
 ):
@@ -284,7 +285,6 @@ async def _obtain_token_for_client(
         return access_token
 
 
-@pytest.mark.integration
 async def test_client_cannot_introspect_other_clients_tokens(
     playwright_oauth_token: str,
     shared_oauth_client_credentials: tuple,
@@ -344,7 +344,6 @@ async def test_client_cannot_introspect_other_clients_tokens(
         )
 
 
-@pytest.mark.integration
 async def test_introspection_with_resource_parameter(
     browser,
     oauth_callback_server,
@@ -440,7 +439,6 @@ async def test_introspection_with_resource_parameter(
         )
 
 
-@pytest.mark.integration
 async def test_introspection_returns_inactive_for_invalid_token(
     test_oauth_clients: dict[str, tuple[str, str]],
     oidc_endpoints: dict[str, str],