Problem

When working with multiple worktrees, stale worktrees accumulate over time — branches get merged, work gets pushed, but the worktrees linger on disk. Cleaning them up manually requires checking each one: is the branch merged? Are there uncommitted changes? Are all commits pushed? This is tedious and error-prone, especially with many worktrees.

Proposal

Add a wtp clean command that provides an interactive way to review and remove worktrees. The command should:

• Validate each worktree against merge status, uncommitted changes, and unpushed commits
• Present a clear overview showing which worktrees are safe to remove and why
• Let the user choose which worktrees to remove via an interactive multi-select
• Pre-select safe worktrees (merged, clean, pushed) so the common case is fast
• Support --force for removing worktrees that have uncommitted changes

Demo

Expected Behavior

$ wtp clean

Select worktrees to remove:
    WORKTREE          STATUS   NOTE
> [x] feature-done   safe     merged, clean, pushed
  [x] bugfix-123     safe     merged, clean, pushed
  [ ] wip-refactor   unsafe   uncommitted changes
  [ ] experiment      unsafe   unpushed commits (3 ahead)

Safe worktrees are pre-selected. Unsafe ones are shown with reasons so the user can make an informed decision.