The IntersectionObserver-on-a-sentinel infinite-scroll pattern was copy-
pasted in 7 places. New composables/useInfiniteScroll(sentinelRef, cb)
owns the observer lifecycle (attach on mount, re-attach when the ref
changes, disconnect on unmount). Migrated GalleryGrid, MasonryGrid
(gallery+showcase), ArtistPostsTab, ArtistsView, TagsView, SeriesManageView.
PostsView left manual on purpose — its anchored mode does bidirectional
scroll-position preservation that doesn't fit the simple composable.
I4(a) (timestamps) is effectively already done: the UTC displays were
converted earlier; the remaining toLocaleString uses already render local
time, so they're left as-is rather than churned for format-only consistency.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
