- Add worktreePath to gitBranchSchema and populate from `git worktree list --porcelain`
- Redirect to existing worktree when selecting a branch that's already checked out
  (instead of failing with "already used by worktree")
- Distinguish main worktree (project cwd) from secondary worktrees in selection logic
- Fix toolbar to show three states: Local, Worktree (existing), New worktree (pending)
- Add explicit protocol/host to Vite HMR config for reliable Electron WebSocket
- Auto-open DevTools in dev mode for HMR debugging

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>