Signals that arrive while the merge confirmation is open show once it closes #377

Current state

Signals that arrive while the merge confirmation is open are lost: after Esc, the list shows the signals from before the confirmation opened until the next refresh. A refresh updates a copy of the list the merge screen keeps but never reads, and closing the confirmation restores the list from a second copy taken when it opened.

Ideal state

• After Esc on the merge confirmation, the list shows the newest signals that arrived while it was open

Decisions

Constraints

No recorded decisions bind this (searched docs/decisions/).

Open

No open decisions.

Starting points

• ui/tui/src/state/update/pr.rs — restores the list from prev when the confirmation closes
• ui/tui/src/state/update/refresh.rs — refresh_screen_in_place, which updates parent instead