Ensure `useLIveInfiniteQuery` works with `on-demand` mode & add cursor support

[KyleAMathews]

I think I saw that offset isn't being incremented correctly atm. Also we need a built-in way for people to do cursor pagination.

[fmal]

yes please, looking forward to have this 🙏 @KyleAMathews i would like to use useLiveInfiniteQuery with on-demand collection to achieve offset-based API paging semantics, but currently the offset is always 0

[KyleAMathews]

I believe this is fixed in current main.

useLiveInfiniteQuery now has on-demand pagination coverage, including async loadSubset, multi-page fetching, and limit + 1 peek-ahead behavior for hasNextPage in packages/react-db/tests/useLiveInfiniteQuery.test.tsx. The sync layer also now exposes cursor/offset pagination hints via LoadSubsetOptions in packages/db/src/types.ts and passes those through from subscription loading in packages/db/src/collection/subscription.ts.

Likely relevant fixing work includes:

• feat(db,electric,query): separate cursor expressions for flexible pagination #960 / b3b19400 — separate cursor expressions for flexible pagination
• fix(db): useLiveInfiniteQuery pagination with async on-demand loadSubset #1209 / 9184dcce — useLiveInfiniteQuery pagination with async on-demand loadSubset
• fix(react-db): useLiveInfiniteQuery deletion not working with descending order on partial page #970 / 41308b8e — related partial-page/deletion pagination behavior

There is some uncertainty because the original issue bundled several pagination concerns, but the current implementation/tests cover the on-demand multi-page/cursor-offset paths this issue was tracking. Closing as fixed; please reopen or file a fresh issue if a specific current cursor/on-demand case is still broken.