ci/lint: ruff format pass and fix compact seed test typing

Apply pending ruff format; narrow AssistantChatMessage.content before
membership checks so basedpyright accepts Unset|None unions.

tests/test_agent/test_loop.py

@@ -617,7 +617,6 @@ async def test_retry_after_resume_orphan_user() -> None:
     await store.close()
 
 
-
 async def test_chat_agent_system_prompt_prepended() -> None:
     from plyngent.lmproto.openai_compatible.model import SystemChatMessage