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/functional/_ghost.py

@@ -93,9 +93,10 @@ class GhostAdmin:
         status, body = self.req(
             "POST", "/session/", {"username": ADMIN_EMAIL, "password": ADMIN_PW}
         )
-        assert status in (200, 201), (
-            f"ghost admin session login failed: HTTP {status}, body={body!r}"
-        )
+        assert status in (
+            200,
+            201,
+        ), f"ghost admin session login failed: HTTP {status}, body={body!r}"
 
     def create_post(self, title: str, html: str) -> dict:
         status, body = self.req(