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/matrix-synapse/functional/test_federation_version.py

@@ -34,12 +34,12 @@ def test_federation_version_endpoint(live_app):
     assert status == 200, f"GET {url} HTTP {status} (expected 200)"
     assert isinstance(body, dict), f"federation version returned non-dict: {type(body).__name__}"
     server = body.get("server")
-    assert isinstance(server, dict), (
-        f"federation version response missing 'server' envelope: {body!r}"
-    )
+    assert isinstance(
+        server, dict
+    ), f"federation version response missing 'server' envelope: {body!r}"
     name = server.get("name")
     assert name == "Synapse", f"server.name={name!r}, expected 'Synapse'"
     version = server.get("version")
-    assert isinstance(version, str) and len(version) > 0, (
-        f"server.version is not a non-empty string: {version!r}"
-    )
+    assert (
+        isinstance(version, str) and len(version) > 0
+    ), f"server.version is not a non-empty string: {version!r}"