Add worktree prune to clean-branches command

[dyoshikawa]

Summary

Add git worktree prune execution to the clean-branches command.

Motivation / Purpose

When working with git worktrees (e.g., via git gtr), stale worktree references can accumulate over time. The clean-branches command already handles branch cleanup and remote pruning, so it's a natural place to also prune stale worktree entries.

Details

Modify .rulesync/commands/clean-branches.md to include a git worktree prune step.

Current steps:

1. Delete all local branches except for current branch and main branch.
2. Run git pull --prune

Proposed steps:

1. Delete all local branches except for current branch and main branch.
2. Run git pull --prune
3. Run git worktree prune

Files affected

• .rulesync/commands/clean-branches.md

Additional Context

N/A