.github/workflows/tests.yml(ci[smoke]): run runtime smoke test

why: ensure CI verifies vcspull installs without dev/test dependencies by running the new smoke script.
what:
- add step that invokes uvx in an isolated environment to run scripts/runtime_dep_smoketest.py.

Author: tony

.github/workflows/tests.yml

@@ -45,6 +45,9 @@ jobs:
           COV_CORE_CONFIG: pyproject.toml
           COV_CORE_DATAFILE: .coverage.eager
 
+      - name: Runtime dependency smoke test
+        run: uvx --isolated --reinstall --from . python scripts/runtime_dep_smoketest.py
+
       - uses: codecov/codecov-action@v5
         with:
           token: ${{ secrets.CODECOV_TOKEN }}