feat: Add Waitlists methods to User Management

[aksman-dev]

Summary

Adds SDK support for the waitlists REST API on workos.userManagement:

• listWaitlists() — GET /user_management/waitlists
• getWaitlist(waitlistId) — GET /user_management/waitlists/:id (accepts the default alias)
• listWaitlistUsers(waitlistId, options?) — GET /user_management/waitlists/:id/entries, with state and exact-email filters plus standard cursor pagination via AutoPaginatable
• createWaitlistUser(waitlistId, payload) — POST /user_management/waitlists/:id/entries with email, optional additionalFields (sent as additional_fields), and optional notify (defaults to false). Idempotent per email; 422 user_already_exists when a user with that email already exists. The default alias lazily creates the default waitlist on this write path.
• approveWaitlistUser(waitlistUserId) — POST /user_management/waitlist_entries/:id/approve
• denyWaitlistUser(waitlistUserId) — POST /user_management/waitlist_entries/:id/deny
• Errors: 422 invalid_state for approve/deny on an entry in the wrong state, 422 invitation_email_not_sent when the approval invitation email cannot be sent
• deleteWaitlistUser(waitlistUserId) — DELETE /user_management/waitlist_entries/:id (204)

Response objects are waitlist and waitlist_user (matching the existing waitlist_user.* webhook events), deserialized to camelCase Waitlist / WaitlistUser types. waitlist_id can be absent or null on legacy entries and is normalized to waitlistId: null.

The new methods are wrapped in @oagen-ignore markers since the API endpoints are excluded from the public OpenAPI spec while incubating.

Warning

Do not merge/release until the waitlist-api feature flag reaches GA (AUTH-6723). The API returns 404 for these routes on teams without the flag, so shipping this early would expose broken methods.

Test plan

• Unit tests with fixtures covering every method: URL/query/body serialization, camelCase deserialization, the default alias, legacy null waitlist_id, and 422 error paths (user_already_exists, invalid_state).
• npm test (917 passed, 12 skipped), npm run lint, npm run prettier, and npm run typecheck all pass.

https://linear.app/workos/issue/AUTH-6719