Optional SessionStore methods raise instead of being absent, so a change in Types reaches 13 modules

Types defines the SessionStore protocol, whose optional methods have default bodies that raise NotImplementedError. Support is detected by checking whether the adapter's class overrides the default (_store_implements), and continue_conversation is refused up front when list_sessions is not overridden. That contract lives in types.py, which 13 of 23 modules on the board depend on, only 3 directly: Control Protocol Query, Session Store and ClaudeSDKClient.

Impact: Changing which SessionStore methods are required, or what their defaults do, silently changes the override check that session validation and resume rely on.

Treat the raising defaults in SessionStore as the definition of 'optional'. Add a new optional method as a raising default, and cover it in session_store_validation so unsupported combinations fail before the subprocess starts.