scripts/test_runtime_dep_smoketest.py(test[smoke]): add pytest wrapper

why: allow CI to invoke runtime dependency smoke test via pytest marker.
what:
- add isolated test harness that shells out with uvx to run the script.
- echo stdout/stderr when the subprocess fails for easier debugging.

Author: tony

scripts/test_runtime_dep_smoketest.py

@@ -0,0 +1,49 @@
+"""Tests for the runtime dependency smoke test script.
+
+These tests are intentionally isolated behind the
+``scripts__runtime_dep_smoketest`` marker so they only run when explicitly
+requested, e.g. ``pytest -m scripts__runtime_dep_smoketest``.
+"""
+
+from __future__ import annotations
+
+import shutil
+import subprocess
+import sys
+from pathlib import Path
+
+import pytest
+
+pytestmark = pytest.mark.scripts__runtime_dep_smoketest
+
+
+def test_runtime_smoke_test_script() -> None:
+    """Run ``scripts/runtime_dep_smoketest.py`` in a clean uvx environment."""
+    uvx = shutil.which("uvx")
+    if uvx is None:
+        pytest.skip("uvx is required to run the runtime dependency smoke test")
+
+    repo_root = Path(__file__).resolve().parents[1]
+    script_path = repo_root / "scripts" / "runtime_dep_smoketest.py"
+
+    result = subprocess.run(
+        [
+            uvx,
+            "--isolated",
+            "--reinstall",
+            "--from",
+            str(repo_root),
+            "python",
+            str(script_path),
+        ],
+        capture_output=True,
+        text=True,
+        cwd=str(repo_root),
+        check=False,
+    )
+
+    if result.returncode != 0:
+        sys.stdout.write(result.stdout)
+        sys.stderr.write(result.stderr)
+
+    assert result.returncode == 0, "runtime dependency smoke test failed"