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/discourse/custom/_discourse.py

@@ -81,9 +81,9 @@ def mint_admin(domain: str) -> tuple[str, str]:
             key = line.split("=", 1)[1].strip()
         elif line.startswith("CCCI_API_USER="):
             user = line.split("=", 1)[1].strip()
-    assert (
-        key and user
-    ), f"could not bootstrap discourse admin/API key; rails output tail:\n{out[-1000:]}"
+    assert key and user, (
+        f"could not bootstrap discourse admin/API key; rails output tail:\n{out[-1000:]}"
+    )
     return key, user