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/discourse/functional/test_create_topic.py

@@ -48,21 +48,23 @@ def test_create_topic_roundtrip(live_app):
         headers=hdrs,
         timeout=60,
     )
-    assert status in (200, 201) and isinstance(body, dict), (
-        f"create topic failed: HTTP {status}, body={body!r}"
-    )
+    assert status in (200, 201) and isinstance(
+        body, dict
+    ), f"create topic failed: HTTP {status}, body={body!r}"
     topic_id = body.get("topic_id")
     assert topic_id, f"create topic returned no topic_id: {body!r}"
 
     # 4) Read the topic back and assert title + first-post body round-trip.
     status, got = harness_http.http_get(f"{base}/t/{topic_id}.json", headers=hdrs, timeout=30)
-    assert status == 200 and isinstance(got, dict), f"read topic failed: HTTP {status}, body={got!r}"
-    assert got.get("title") == title, (
-        f"topic title did not round-trip: sent {title!r}, got {got.get('title')!r}"
-    )
+    assert status == 200 and isinstance(
+        got, dict
+    ), f"read topic failed: HTTP {status}, body={got!r}"
+    assert (
+        got.get("title") == title
+    ), f"topic title did not round-trip: sent {title!r}, got {got.get('title')!r}"
     posts = (got.get("post_stream") or {}).get("posts") or []
     assert posts, f"topic has no posts on read-back: {got!r}"
     first_cooked = posts[0].get("cooked", "")
-    assert marker in first_cooked, (
-        f"topic body did not round-trip: marker {marker!r} not in first post {first_cooked!r}"
-    )
+    assert (
+        marker in first_cooked
+    ), f"topic body did not round-trip: marker {marker!r} not in first post {first_cooked!r}"