chore: add ty + pre-commit hook and repeal even more ruff rules (#9504)

* auto fixes

* auto fix pt2 and transitive deps and undefined var checking locals()

* manual fixes (ignored or letta-code fixed)

* fix circular import

* remove all ignores, add FastAPI rules and Ruff rules

* add ty and precommit

* ruff stuff

* ty check fixes

* ty check fixes pt 2

* error on invalid

tests/test_prompt_caching.py

@@ -542,7 +542,7 @@ async def test_prompt_caching_cache_invalidation_on_memory_update(
 
     try:
         # Message 1: Establish cache
-        response1 = await async_client.agents.messages.create(
+        await async_client.agents.messages.create(
             agent_id=agent.id,
             messages=[MessageCreateParam(role="user", content="Hello!")],
         )