test: scaffold pytest suite with mise, uv and Task

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

tests/test_scaffold.py

@@ -0,0 +1,12 @@
+"""Scaffold checks: prove the gating logic itself. Real tests follow in later commits."""
+
+import pytest
+
+
+def test_image_is_available(image):
+    assert image
+
+
+@pytest.mark.feature("bash")
+def test_feature_gate_probe(detected_features):
+    assert "bash" in detected_features