Add Zed editor support across open-in flow

- add `zed` to shared editor contracts and Open In picker
- add Zed icon and wire launch resolution tests on macOS
- wrap branch optimistic updates in `startTransition` to avoid sync warnings
4a08686e74Julius Marminge committed on 3/3/2026, 2:53:21 AM· committed by Julius Marmingeparentb3de2bd
5 files changedLine totals unavailable