Agent Skills: wt-switch-create

Create a new worktrunk worktree (optionally in another repo) and switch this session's working directory into it. Use when launching a session that should work in its own worktree (e.g. `/wt-switch-create my-branch -- <task>`, or `/wt-switch-create my-branch ~/workspace/other-repo -- <task>`), or mid-session to move work into a fresh branch.