Current per-SKU usage vs. plan quotas for the caller org

Returns the plan id, the plan-author quota map (perMinute / perDay), and for every SKU with a quota the current open-window counts plus their reset timestamps. `minuteUsed` is the in-flight minute bucket; `dayUsed` is the last-24h durable sum + current minute — the same arithmetic `QuotaGuard` uses to decide 429. A `null` limit means the plan left that window unlimited.