feat: add REPO and PLAYLIST columns to runbox list --all-repos

[proboscis]

Summary

Enhances runbox list --all-repos to show additional context columns:

• REPO column: Repository URL (truncated to 20 chars)
• PLAYLIST column: Playlist display name for playlist items

Fixes ISSUE-038

Changes

• Added playlist_name field to RunnableInfo struct
• Added get_runnable_playlist_name() method to Storage
• Updated table output to show extra columns when --all-repos or --verbose is used
• JSON output includes repo_url and playlist_name fields

Evidence

=== List with --all-repos (shows REPO and PLAYLIST columns) ===
SHORT      TYPE       SOURCE           NAME                     TAGS   REPO                 PLAYLIST
──────────────────────────────────────────────────────────────────────────────────────────────────────────────
383ca926   template   -                Echo Test                -      git@github.com:us... -
1aa7870b   template   -                Game CLI                 -      git@github.com:us... -
d05ba50f   playlist   game_run[0]      Run Game                 -      git@github.com:us... Card Game 2026

Testing

• All 121 unit tests pass
• All integration tests pass
• Manual testing verified