Lists the memberships of a user within the accessible organisation subtree, paginated and in stable order.

This is the volume-proof alternative to GET /v1/users/USER_ID?include=memberships: the include is
capped at 1,000 accessible memberships, while this listing retrieves any number of memberships page by page.

A target user with no membership in the accessible subtree returns a 403.

🔒 This endpoint requires an OAC (Organisation Access Credentials — ⚠️ Beta) access token with the users:read scope.