Get Agent Desk Usage

AGENTDESK-P2(PR-C): the customer-visible usage readout for the desk Overview.

Two numbers plus the honesty around them:

• answers_today / answers_limit → "N of X answers today". Both may be None and the two Nones mean DIFFERENT things, which is why they are separate fields rather than a formatted string: a None limit means uncapped (render "N answers today", no ratio), a None usage means we could not read the counter (render "—", never 0).
• published_pages / published_pages_included → the billable count and what the plan includes. This resource is never enforced; the included figure is an allowance, and overage bills as subscription quantity.
• answers_period → the period-scoped bundle (Option C). None when no bundle applies to this plan OR the read failed — the UI omits the line rather than inventing a number.
• can_pick_subdomain → whether the plan entitles the customer to configure the desk's exact subdomain label (Growth/Scale; Starter stays on the "agents" default). Read through usage_limits.plan_allows_custom_subdomain, the same reader the hosting routes' 403 gate uses — so the picker the UI shows and the write the server accepts cannot disagree. Defaults False: an unreadable plan row renders the upsell line, never a control the save would then refuse.