- Add WorktreePath and WorktreeBranch fields to TaskDTO
- Add WorktreeLookup interface to TaskController for enriching task responses
- Add GetWorktreeInfo method to worktree.Manager implementing WorktreeLookup
- Wire worktree manager to task controller in main.go
- Add worktree_path and worktree_branch to frontend Task type
- Display worktree path with copy button in TaskTopBar when worktree exists
- Show worktree branch in tooltip for easy reference
- Add worktree package with Manager, Store, Config, and error types
- Integrate worktree creation/reuse into lifecycle manager
- Update executor to pass worktree configuration
- Add WorktreeConfig to common config package
- Enable worktrees by default for agent isolation
- Add unit tests for worktree manager
This allows multiple agents to work on the same repository simultaneously
by creating isolated worktrees for each task. Worktrees persist between
agent runs for task resumption and are only cleaned up when tasks are
explicitly deleted.