List mob names in purge confirmation prompt

[blipinsk]

Closes #35

adds listing of mobs to be deleted in the purge operation:

❯ codemob purge

  ⚠ DESTRUCTIVE OPERATION

  The following mobs will be permanently removed:

    NAME              BRANCH
    epic-dragonfruit  mob/epic-dragonfruit
    dark-lime         mob/dark-lime
    test-test         mob/test-test
    loud-grape        mob/loud-grape
    rough-radish      mob/rough-radish
    daring-jackfruit  mob/daring-jackfruit
    zippy-banana      mob/zippy-banana
    epic-fig          fix/mob-remove-non-interactive
    shy-fig           purge-list-mobs

  Any uncommitted or unpushed changes in those worktrees will be permanently lost.

  This cannot be undone.

  Are you sure? [y/N]:

Summary

• codemob purge now lists each mob by name in the confirmation prompt instead of just showing a count
• Helps the user see exactly what they're about to delete before confirming

Test plan

• Existing TestPurge extended to verify mob names appear in output
• All purge-related tests pass