chore: apply linting fixes and expand ruff coverage to test suite

src/pygui/backend/wafer/wafer_layouts.py

@@ -69,6 +69,12 @@ def _load_yaml(path: Path) -> dict:
         return yaml.safe_load(f)
 
 
+# TODO P6.3: expose this list to a new LayoutSelector.qml (4-button chooser)
+#   THINKING: this already returns everything the UI needs (family names) —
+#   the missing piece is a context-property exposure (SessionController or a
+#   thin new property) and a setLayout(family) slot that calls load_layout()
+#   below. No parsing work needed; this is a wiring-only task.
+#   See docs/pending/alpha-release-polish-plan.md §6.3.
 def available_families() -> list[str]:
     return [_family_name(_load_yaml(p)["name"]) for p in _LAYOUTS_DIR.glob("*.yaml")]