- Replace per-operation thread spawning with a single persistent
asyncio event loop (saves ~10-50ms per async operation)
- Pre-scan saved directories into sets instead of per-post
exists() calls (~80+ syscalls reduced to a few iterdir())
- Add add_favorites_batch() for single-transaction bulk inserts
- Add missing indexes on favorites.folder and favorites.favorited_at
Supports Danbooru, Gelbooru, Moebooru, and e621. Features include tag search
with autocomplete, favorites with folders, save-to-library, video playback,
drag-and-drop, multi-select, custom CSS theming, and cross-platform support.
