feat: manual albums + gallery multi-select with bulk actions

Albums (manual collections):
- New albums/album_images tables with FK cascades; DB functions and Tauri
  commands for create/rename/delete/delete-many/reorder/list, add/remove
  images, and paginated get_album_images.
- Distinct sidebar "ALBUMS" section with cover thumbnails, create/rename/
  delete, and a Manage multi-select mode for bulk album deletion.
- Album view reuses the gallery grid (activeView "album" + selectedAlbumId);
  spans folders; add from the bulk bar or the lightbox, remove from within.

Gallery multi-select + bulk actions:
- gallerySelectedIds selection model with a top-left corner checkbox that
  reveals on corner hover; click-to-toggle in selection mode, double-click
  to open.
- Floating BulkActionBar: tag (inline autocomplete popover), rating,
  favorite, add-to-album, and a delete with an explicit "from disk"
  confirmation. Batch commands bulk_update_details/bulk_add_tags/
  bulk_remove_tag.

Also:
- Duplicate Finder delete now requires confirmation with clear "from disk"
  wording (was single-click fire-and-forget).
- CPU/CUDA build-variant badge in Settings (get_build_variant).
- Rating/favorite no longer re-sorts derived collections (similar/region/
  semantic/tag/album results); single and bulk paths replace in place there.
- Album-aware indexed-images/media-updated handlers so thumbnails paint and
  newly-indexed files don't leak into an album view.
- CHANGELOG updated.

src-tauri/src/lib.rs

@@ -185,6 +185,19 @@ pub fn run() {
             commands::get_image_tags,
             commands::add_user_tag,
             commands::remove_tag,
+            commands::list_albums,
+            commands::create_album,
+            commands::rename_album,
+            commands::delete_album,
+            commands::delete_albums,
+            commands::reorder_albums,
+            commands::add_images_to_album,
+            commands::remove_images_from_album,
+            commands::get_album_images,
+            commands::bulk_update_details,
+            commands::bulk_add_tags,
+            commands::bulk_remove_tag,
+            commands::get_build_variant,
             commands::search_tags_autocomplete,
             commands::find_duplicates,
             commands::load_duplicate_scan_cache,