Track per-terminal subprocess activity in thread state

- subscribe to terminal events in root route and dispatch terminal activity updates
- add reducer support to maintain `runningTerminalIds` per thread/terminal
- add unit tests for terminal event mapping and store activity state transitions
c9017090e5Julius Marminge committed on 2/27/2026, 3:35:32 AMparent23d2a8a
5 files changedLine totals unavailable