acp_thread: Mark in progress plan items as pending (#52196)

## Context

We were seeing some off by one errors because we weren't counting in
progress as either pending or completed.

Release Notes:

- acp: Fix plan stats showing all tasks as done when items were still in
progress.
b423194ecdBen Brandt committed on 3/23/2026, 12:41:20 PM· committed by GitHubparent841ca10
1 file changedLine totals unavailable