Maho_Ai_Model_TaskCallbackInterface
in
Implemented by classes that handle async task completion callbacks.
Submitters set callback_class / callback_method on a task row; the
TaskRunner instantiates callback_class after the AI provider returns
and invokes callback_method. Requiring this interface ensures only
classes explicitly marked as task callbacks can be instantiated by the
runner — closing off arbitrary-class instantiation via a crafted task
row.