API: expose which boards a user can access

In the UI I can give a user Org Admin or Admin and pick which boards they can access.

In API v3 that board list is missing:

• GET /users has role (org_admin / editor) but no boards

• GET /boards and GET /boards/{id} have board details but no assigned users

• POST /boards and PATCH /boards/{id} accept user_ids to set access, but nothing returns those assignments

Please add a way to read which boards a user has access to. For example board_ids on GET /users