Cap thread terminals at four and disable add/split controls

- enforce max 4 terminals per thread in reducer and terminal normalization
- block split/new terminal actions in chat and drawer when limit is reached
- add reducer tests for split/new terminal cap behavior
376efdd340Julius Marminge committed on 2/18/2026, 12:05:59 AM· committed by Julius Marmingeparent7a5dd62
5 files changedLine totals unavailable