Spinner persists after /clear command

Bug

When a background agent/task is running and the user executes /clear, the conversation context is cleared but the spinner from the previous task continues to display (e.g., ✶ Embellishing… (5m 48s · 3.5k tokens)).

Expected behavior

/clear should cancel any active spinners/progress indicators along with clearing the conversation.

Actual behavior

The spinner from the previously running agent continues ticking indefinitely after /clear, even though the conversation context has been reset.

Steps to reproduce

1. Start a task that spawns a background agent or long-running operation
2. While the spinner is active, run /clear
3. Observe the spinner continues to display

Environment

• Platform: macOS (Darwin 25.3.0)
• Model: claude-opus-4-6