Pagination docs were scattered across api-types.md (types + cursor
semantics), data-api-in-renderer.md (hooks), data-api-in-main.md (offset
example + keyset note), api-design-guidelines.md (query params), and
data-ordering-guide.md (cache shapes + determinism), with no single
discoverable home for the offset-vs-cursor model.
Add docs/references/data/data-pagination-guide.md as the canonical hub
(mirrors data-ordering-guide.md): two modes, four-layer quickstart, wire
contract, server impl (offset + keyset cursor + multi-band caveat),
renderer consumption, FTS pagination, gotchas, and a see-also map. Other
docs keep their authoritative slice and link to the guide; the migrated
conceptual prose is removed from api-types.md to avoid duplication.
Also fix two pre-existing broken anchors found while verifying links
(database-patterns withWriteTx; ordering guide section number).
