fix: publish ./pagination subpath with helpers and CursorPage type (Closes #411)

[Zhiyilang074811]

Summary

Publishes the existing ./pagination\ subpath through \package.json\ exports and \src/index.ts, making \parseCursorPage, \�uildPaginationQuery, \paginate, and \CursorPage\ available to consumers.

Changes

• package.json: Added ./pagination\ export entry with import/CJS/type conditions matching the existing pattern
• src/index.ts: Added re-exports for all four pagination symbols
• test/dist-smoke.mjs: Added runtime checks for all four exports in both ESM and CJS
• tests/api-report-snapshot.test.ts: Added \pagination.d.ts\ to the subpath .d.ts existence check
• tests/exports-subpath-resolves.test.ts: Added ./pagination\ to the expected subpaths assertion

Acceptance Criteria

• Importing the three helpers and \CursorPage\ from the ./pagination\ subpath works against the built package
• The emitted \pagination.d.ts\ contains the full typed signatures (via tsconfig declarations)
• The exports-subpath and dist smoke tests cover ./pagination\

Closes #411

[Zhiyilang074811]

Hi! Friendly ping — open for ~2 days, all checks passing. Ready for review when convenient. Thanks! 🙏