B1: `createComposerState` always typed the initial media as `ImagesMedia`
regardless of `initImageUris.length`. With the picker cap raised to 10 in
ComposerPrompt + the URL intent handler not capping at all, the FAB and
deep-link flows could land the composer with 5-10 images in an `images`
embed, which `app.bsky.embed.images` rejects (`maxLength: 4`) on submit.
Extract `imagesToMediaVariant` and reuse from `createComposerState`,
`embed_add_images`, and `embed_remove_image` so the variant decision
("<=4 = images, >4 = gallery, cap at 10") lives in one place. The
remove-image demote branch collapses into the helper too — same effect,
less code.
W1: `maybeApplyGalleryOffsetStyles` only short-circuited single-image
galleries, applying offset for 0-item galleries when nothing renders
below. Loosened to `<= 1` (covers both 0 and 1 with the same intent).
vineyardbovines
4fe5f9da37