Handle branch selection across main and secondary worktrees

- add `resolveBranchSelectionTarget` to unify checkout cwd/worktree decisions
- reuse existing worktrees when available, including switching back to main repo
- update branch selector to use shared logic and add targeted unit tests
9bb9023009Julius Marminge committed on 3/10/2026, 5:50:45 AM· committed by Julius Marmingeparentf70cb5d
3 files changedLine totals unavailable