bug: the wishlist badge read /wishlist/counts 'total', which was movies+episodes
only — YouTube videos (kind='video') are counted by a separate method and were
left out. so a wishlist of only youtube videos showed NO number; it only lit up
once tv episodes were added.
fix: the /wishlist/counts endpoint now folds youtube_wishlist_counts().video into
the total (+ exposes video/channel counts). the badge already live-refreshes on
wishlist-changed events (which youtube add/remove fire), so it now updates for
youtube too. db methods unchanged (their byte-identical contract is intact).
regression tests: mixed + youtube-only.
3fa7b48f4c