- Add adm-zip dependency for zip compression
- Add DownloadAllZipParams/Result IPC types
- Implement registerDownloadAllZip handler in main process
- Update frontend download flow with save dialog
- ZIP includes pc/, mobile/ folders and metadata.json
- Remove @lobehub/i18n-cli package and .i18nrc.js config
- Delete locales/default/ directory (translation source)
- Change DEFAULT_LOCALE and fallbackLng to ja-JP
- Reorder LOCALES array with Japanese first
- Simplify language selector to horizontal solid button style