Both were redundant:
- "N selected" is already shown by the contextual KeyboardHints pill
below the FilterBar
- The Discard action is in the RightSidebar Flag section and bound
to X (and exists as a per-photo button on the thumbnail when
is_discarded)
Also removes the no-longer-used discardPhotosMutation, the photos
api import, the toast import, the useMutation/useQueryClient imports,
and the usePhotoStore selectedPhotos read — TopBar is leaner now.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>