Both the primary and the interjection sub-stream in
``regenerate_assistant_turn`` are now wrapped in ``asyncio.create_task``
and registered in the chat-keyed ``_in_flight_tasks`` registry that the
``/turns/cancel`` route reads. Without this, hitting Stop during a
mid-regenerate stream was a no-op.
Mirrors the meanwhile registration pattern in chat/web/meanwhile.py
(snapshot-tested by tests/test_meanwhile_turn_flow.py).
Test added: test_regenerate_registers_task_in_in_flight_tasks captures
``"chat_bot_a" in _in_flight_tasks`` at the first stream yield via a
custom MockLLMClient subclass and asserts post-flight cleanup.
Joseph Doherty
f2fd30c5a9