[Bug]: Plan action label says "Implement in new thread" instead of "Implement in a new thread"

[UtkarshUsername]

Before submitting

• I searched existing issues and did not find a duplicate.
• I included enough detail to reproduce or investigate the problem.

Area

apps/web

Steps to reproduce

1. Open a thread in plan mode.
2. Tell the AI to write a plan.
3. Open the menu next to the Implement button.
4. Observe the secondary action label.

Expected behavior

The menu label should read Implement in a new thread.

Actual behavior

The menu label reads Implement in new thread.

Impact

Cosmetic issue

Version or commit

0.0.11

Environment

No response

Logs, stack traces, or screenshots

Workaround

No response

[UtkarshUsername]

Fixed by #1063