lint: ruff format + one auto-fix so the push self-test is green again

`scripts/lint.sh --fix` from the pinned lint devshell: 90 Python files
reformatted (ruff format, mechanical) and one C420 (dict comprehension →
dict.fromkeys) in tests/unit/test_f211_sso_skip.py. The push self-test had
been failing at the lint stage since build 1313 (2026-08-31) on exactly
these files; nothing else changed.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FqkQq3CDmFWcQ7u1LzoyRz

tests/gitea/test_upgrade.py

@@ -20,6 +20,6 @@ def test_upgrade_preserves_marker_repo(live_app, meta):
     """The ci-marker repo survived the upgrade to the PR head (data continuity)."""
     generic.assert_serving(live_app, meta)
     user, password = admin_creds(live_app)
-    assert marker_repo_exists(
-        live_app, user, password
-    ), f"{live_app}: ci-marker repo did not survive the upgrade (sqlite3 data lost)"
+    assert marker_repo_exists(live_app, user, password), (
+        f"{live_app}: ci-marker repo did not survive the upgrade (sqlite3 data lost)"
+    )