Cursor pagination — Phase 1: backward-compatible compat layer

[lucy-meachem]

Goal

Add cursor-based pagination support (x-has-more / x-next-cursor response headers) to the SDK's central pagination plumbing, backward-compatibly alongside the existing offset/x-total-count pagination. Ships first, before any backend change — it alters no endpoint behaviour.

Scope (Phase 1)

Core plumbing only — the three central pagination files plus a bulk helper:

• Connection — parseResponse reads x-has-more / x-next-cursor and wraps the body as { list, hasMore, nextCursor } when present (offset x-total-count path unchanged).
• Paginated — add optional nextCursor + hasMore; hasNextPage() prefers hasMore over the endReached heuristic.
• List.getNextPaginated — thread cursor (from previous.nextCursor) into the callback; derive endReached from hasMore when provided.
• List.getAllPaginated — new loop helper that follows cursors until hasMore is false (for bulk fetchers in Phase 2).
• Full test + build gate: npx jest, npx tsc -p . --noEmit, npm run lint.

All additive: responses without cursor headers behave exactly as today, so this is safe to release before the backend moves.

Confirmed decisions

• Cursor sent back as the cursor query param.
• Coexistence: SDK handles both offset and cursor responses.
• Forward-only (no prev/jump-to-page).
• No sort param on cursor endpoints (fixed server-side).

Not in this phase

Endpoint call-site migration → Phase 2 (#442).

References

• Design: docs/superpowers/specs/2026-07-02-cursor-pagination-design.md
• Plan (Tasks 1–4, 7): docs/superpowers/plans/2026-07-02-cursor-pagination.md