Skill: Backup Library

Backups default to ~/Documents/buttercut-video-editor-backups. Each library gets its own subdirectory there, and each run drops a timestamped archive of just that one library — so adding a new clip to one library only writes that library's archive, not a full duplicate of everything.

~/Documents/buttercut-video-editor-backups/
  wedding/
    wedding_20260520_140000.aar
  programmer-story-vlog/
    programmer-story-vlog_20260520_140000.aar

Step 1 — Resolve the destination

Read backups_dir from libraries/settings.yaml. If the key is missing, ask the user with AskUserQuestion whether to use the default (~/Documents/buttercut-video-editor-backups, recommended) or a custom folder, and save the answer to libraries/settings.yaml under backups_dir. If libraries/settings.yaml doesn't exist yet, create it from templates/settings_template.yaml first.

When invoked from another skill that must stay non-interactive (e.g. process-library auto-backup) and backups_dir isn't set, skip the prompt and use the default — the user can change it later.

Step 2 — Run the backup