- Add rehydrate() method and scanIdleWorktrees() to restore idle worktrees from disk on startup
- Add cleanupOrphanedWorktrees() to remove stale worktrees when recycling is disabled
- Wire startup rehydrate/cleanup into dashboard command based on recycleWorktrees setting
- Export new functions from @kb/engine and update dashboard imports
- Add unit tests for rehydrate/scan/cleanup and integration tests for restart resilience
- Rename npm packages from @kb/* to @hai/* and update all workspace references
- Rename CLI binary from kb to hai and config directory from .kb to .hai
- Update dashboard UI branding, titles, and references from kb to hai
- Update all test files, CI workflows, and documentation to reflect new naming
- Run comprehensive grep verification to ensure no stale kb references remain
- Add recycleWorktrees setting to control worktree pooling behavior
- Implement WorktreePool class with acquire/release/prepareForTask lifecycle
- Integrate pool into executor: acquire warm worktrees, skip init command for pooled entries
- Integrate pool into merger: release worktrees to pool instead of removing on task completion
- Add comprehensive unit and integration tests for pool, executor, and merger interactions
