Keep monitored threads out of the Working section

[Sma-Das]

With Working section on, a thread whose turn has finished and is only waiting on a monitor sits in the collapsed Working section. A pull request watch is the usual case. The agent is idle. The thread can stay there for hours, until a check, a comment, or a merge wakes it.

Those threads should leave Working while that setting is on. Either placement is fine:

• Their own Monitored section in the sidebar.
• The active list, with the other threads that are finished or waiting on me.

A thread that is still running, or waiting on a subagent, should stay in Working. A pin should stay pinned. With the setting off, the sidebar stays as it is.

When the monitor wakes the agent and a turn starts, the thread belongs in Working again. When that turn needs an answer or finishes, it returns to the active list the same way other threads do.

The user guide currently says this section holds threads that are working or monitoring, and watch_pull_request tells the agent the thread stays in Working for the watch. Both should follow whichever placement you pick.

Discussion #15433 asks whether background commands should hold a thread in Working. Commands already leave. This request is the other way for monitors, which currently stay.

[JoshAntBrown]

Same here. A thread watching its own PR sat in Working waiting on a human review.

A possible middle ground with #16204: keep the watch counting as Working while the PR is active, and drop the thread back to the active list once it has been quiet for some time. The watch stays on, so a late review still wakes the agent. Review rounds don't flicker, and a stalled PR can't hide indefinitely. #16262 already logs quiet time, which could set the threshold.