feat(webui): test coverage and CI gate (#436)

Add consolidated MVP route/read-only tests, path-filter helpers, and
scripts/test-webui plus scripts/ci-webui-check for Jenkins path-filtered
runs on PRs touching web UI surfaces.

Closes #436

docs/webui-local-dev.md

@@ -155,4 +155,25 @@ pytest tests/test_webui_skeleton.py tests/test_webui_project_registry.py tests/t
 pytest tests/test_webui_skeleton.py tests/test_webui_project_registry.py tests/test_webui_prompt_library.py tests/test_webui_queue_dashboard.py tests/test_webui_lease_visibility.py tests/test_webui_runtime_health.py -q
 
 pytest tests/test_webui_skeleton.py tests/test_webui_project_registry.py tests/test_webui_prompt_library.py tests/test_webui_queue_dashboard.py tests/test_webui_deployment_boundary.py -q
+
+## Tests (#436)
+
+Run the full hermetic web UI suite (all `test_webui_*.py` modules):
+
+```bash
+./scripts/test-webui
+```
+
+CI / Jenkins multibranch can call the path-filtered gate (runs only when the
+diff touches `webui/`, `tests/test_webui_*`, or web UI docs/scripts):
+
+```bash
+./scripts/ci-webui-check
+WEBUI_CI_FORCE=1 ./scripts/ci-webui-check   # always run
+```
+
+Or invoke unittest directly:
+
+```bash
+python3 -m unittest discover -s tests -p 'test_webui_*.py' -q
 ```