List tenant plans sorted by creation date

Returns the first page of plans belonging to the specified tenant, sorted by creation date descending (most recent first). Call this to retrieve the current plan catalogue for a tenant. The caller must hold the READ_PLAN permission. Note: the current implementation always queries page 0 with a fixed page size of 10; pagination parameters are not exposed on this endpoint, so if the tenant has more than 10 plans, only the 10 most recent are returned. If the tenant has no plans, data is empty and totalCount is 0 (a downstream 404 is silently mapped to an empty result).