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/manual_test_many_messages.py

@@ -17,7 +17,7 @@ from letta.server.server import SyncServer
 
 @pytest.fixture(autouse=True)
 def truncate_database():
-    from letta.server.db import db_context
+    from letta.server.db import db_context  # type: ignore[attr-defined]
 
     with db_context() as session:
         for table in reversed(Base.metadata.sorted_tables):  # Reverse to avoid FK issues