style: repo-wide lint pass — make the lint gate green again

Push builds have been RED on the lint step since ~build 209 from accumulated
formatting drift. This is the mechanical cleanup: ruff format + ruff --fix
(UP038 isinstance unions, SIM105 contextlib.suppress, UP031 f-strings, SIM115
tempfile context manager), shfmt -i 2 -ci, nixpkgs-fmt/statix/deadnix (merged
attrsets, dropped unused lib args), yamllint, and shell quoting fixes in
tests/lasuite-docs/setup_custom_tests.sh. No behaviour changes intended;
lint: PASS, unit tests: 138 passed.

tests/unit/test_results.py

@@ -275,7 +275,9 @@ def test_build_results_threads_expected_na(tmp_path):
     assert data["level_cap_rung"] == "backup_restore"
     assert data["rungs"]["functional"] == "pass"
     assert data["skips"]["intentional"]["backup_restore"] == "stateless static file server"
-    assert data["skips"]["unintentional"] == []  # backup_restore declared; functional passed → clean
+    assert (
+        data["skips"]["unintentional"] == []
+    )  # backup_restore declared; functional passed → clean
 
 
 def test_write_results_roundtrip(tmp_path):