Stabilize ChatView attachment height browser test with MSW

- Run ChatView browser tests through the real app router/store stack
- Add MSW worker setup and mocked WS/attachment responses for full-app rendering
- Extract shared `getRouter` setup and add a timeline root data hook for reliable measurement
f5bdc138f6Julius Marminge committed on 3/5/2026, 6:20:34 PM· committed by Julius Marmingeparent2d8ca48
9 files changedLine totals unavailable