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/ghost/recipe_meta.py

@@ -63,7 +63,11 @@ def BACKUP_VERIFY(domain):
     try:
         out = lifecycle.exec_in_app(
             domain,
-            ["sh", "-c", "gzip -t /var/lib/mysql/backup.sql.gz && wc -c < /var/lib/mysql/backup.sql.gz"],
+            [
+                "sh",
+                "-c",
+                "gzip -t /var/lib/mysql/backup.sql.gz && wc -c < /var/lib/mysql/backup.sql.gz",
+            ],
             service="db",
             timeout=60,
         ).strip()