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.

runner/nightly_sweep.py

@@ -60,14 +60,17 @@ def sweep() -> int:
     for r in recipes:
         print(f"\n===== nightly: full-cold {r} (latest) =====", flush=True)
         env = dict(os.environ, RECIPE=r)
-        env.pop("REF", None)      # latest, not a PR head
+        env.pop("REF", None)  # latest, not a PR head
         env.pop("CCCI_QUICK", None)
         env.pop("MODE", None)
         rc = subprocess.run(
             [sys.executable, os.path.join(_here(), "run_recipe_ci.py")], env=env
         ).returncode
         results[r] = rc
-        print(f"nightly: {r} rc={rc} ({'green→canonical refreshed' if rc == 0 else 'red'})", flush=True)
+        print(
+            f"nightly: {r} rc={rc} ({'green→canonical refreshed' if rc == 0 else 'red'})",
+            flush=True,
+        )
     # WC8 disk hygiene: drop warm data for de-enrolled canonicals; log the disk budget.
     pruned = canonical.prune_stale()
     if pruned: