Task list not reset when session is rewound

Description

When a session is rewound (conversation and code changes are reset to a prior point), the task list retains its state from before the rewind. Tasks that were marked as in_progress or completed remain in that state even though the associated work no longer exists.

Steps to Reproduce

1. Start a session and create tasks via the task list
2. Begin working on tasks (mark some as in_progress or completed)
3. Rewind the session to a point before the tasks were worked on
4. Check the task list — tasks retain their pre-rewind status

Expected Behavior

When a session is rewound, the task list should be reset to match the state at the rewind point, consistent with how conversation history and code changes are reset.

Actual Behavior

Task list retains stale status values from the pre-rewind timeline. This requires manually resetting each task back to pending.

Impact

• Confusing UX: the task list says work is done that doesn't exist
• Requires manual cleanup to get back to a clean state
• Could lead to skipped work if the stale status isn't noticed

Version

Behavior verified with version 2.1.42