fix(trail): harden create --checkout follow-up and switch hint

main

Commit

peyton-altyesterday
  • A print failure after creation names trail #N (ID) and says not to rerun.
  • When checkout errors but HEAD moved (failing post-checkout hook), report the switch instead of asking for another one.
  • Names altered by display sanitizing (bidi/format runes) get a hint without a runnable git switch command.
  • A branch held by another worktree: the hint points to that worktree, and --checkout refuses before anything is published or created.

Co-Authored-By: Claude Opus 5.5 noreply@anthropic.com Claude-Session: https://claude.ai/code/session_01XJeHKftfKHD7hSi6ZxJww8 Entire-Checkpoint: 01M6KYENCS1FAETB36BK3DQ61Q