fix(gtea): ruff format + check all gtea files and bridge.py

Clears cc-ci self-test lint failures:
- ruff format: 9 files reformatted (all gtea test files + test_discovery.py)
- ruff check --fix: bridge.py UP017 (datetime.UTC alias) + 6 gtea check errors
- manifest.py B007: rename unused loop variable path → _path (no auto-fix available)

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

tests/unit/test_discovery.py

@@ -106,7 +106,11 @@ def test_custom_tests_prefers_custom_and_warns_on_deprecated_aliases(tmp_path, m
 
     customs = discovery.custom_tests(fake_recipe, None)
 
-    assert [os.path.basename(path) for _, path in customs] == ["test_a.py", "test_b.py", "test_c.py"]
+    assert [os.path.basename(path) for _, path in customs] == [
+        "test_a.py",
+        "test_b.py",
+        "test_c.py",
+    ]
     err = capsys.readouterr().err
     assert "deprecated folder 'functional/'" in err
     assert "deprecated folder 'playwright/'" in err