Remove approximate processing times from remove-bg quality options.
Update tool count from 37 to 33 across README, settings dialog, login
page, and i18n strings to reflect the accurate count.
Remove docs/superpowers/, .claude/ config, and PRD.md from version
control (kept locally via .gitignore). Update README, CHANGELOG,
VitePress docs, and .env.example to reflect recent features: Files
page, teams, admin settings, persistent storage, and various API
improvements.