test: sync stale fixtures and isolate openclaw env tests

Three unrelated test failures surfaced after rebase:

- McpFormModal expected the apps boolean set without `hermes`; Hermes MCP
  support is now wired, so the fixture must include `hermes: false`.
- therouter Gemini preset was bumped to `gemini-3.1-pro` in a later
  commit; update the assertions to match current config.
- openclaw_config tests mutate process-level `CC_SWITCH_TEST_HOME` and
  `HOME` inside a module-local Mutex, but hermes_config does the same
  under its own separate Mutex. Running both modules in parallel let the
  env races corrupt hermes_config's `with_test_home`. Tag the four
  env-mutating openclaw tests with `#[serial]` so they serialize across
  modules via serial_test's process-wide default key.

tests/components/McpFormModal.test.tsx

@@ -434,6 +434,7 @@ type = "stdio"
       gemini: false,
       opencode: false,
       openclaw: false,
+      hermes: false,
     });
     expect(onSave).toHaveBeenCalledTimes(1);
     expect(toastErrorMock).not.toHaveBeenCalled();