The /api/admin/wipe/gallery branch deleted GalleryImage rows but left
every GalleryAlbum row behind (GalleryAlbum wasn't even imported). After
"wipe gallery" the user is left with orphaned, empty albums whose cover_id
points at now-deleted images — inconsistent with the other wipe branches,
which clear both parent and child tables.
Delete GalleryAlbum alongside GalleryImage and include both in the
returned count.
Adds tests/test_admin_wipe_gallery.py: seeds a real in-memory SQLite DB
with an album + image, runs the actual wipe handler, and asserts both
tables are emptied. Fails before this change (albums survive).
