fix: address second round of review feedback

- Remove dead monkeypatch in test_stdio_calls_get_stdio_mcp
- Add _reload_config() teardown to single_user_env fixture
- Tighten AVAILABLE_APPS type to Callable[[FastMCP], None]

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

tests/unit/test_stdio.py

@@ -17,6 +17,8 @@ def single_user_env(monkeypatch):
     # Ensure multi-user mode is off (may leak from other tests)
     monkeypatch.delenv("ENABLE_MULTI_USER_BASIC_AUTH", raising=False)
     _reload_config()
+    yield
+    _reload_config()
 
 
 @pytest.mark.unit