Desktop app: session turn timer continues counting after response completes

Bug Description

The session turn timer (the "23s" counter next to the pulsing Claude asterisk icon) continues counting after a response has been fully delivered. The timer should stop when the response is complete, but it keeps incrementing even after the full response text is visible to the user.

Steps to Reproduce

1. Open Claude Code desktop app
2. Send a message that involves tool use (builds, bash commands, file edits)
3. Wait for the full response to be delivered
4. Observe the turn timer next to the asterisk icon — it continues counting

Expected Behavior

The timer should stop when the response is fully delivered.

Actual Behavior

The timer keeps incrementing after the complete response text is visible. This appears to be a UI rendering bug where the "streaming complete" event doesn't properly stop the timer animation.

Environment

• App: Claude Code desktop app (macOS)
• OS: macOS (Darwin 25.4.0)
• Context: Normal conversation session with tool use. No background tasks running when the bug was observed.