Manage subscription lifecycle in Bunny. Covers the state machine (PENDING → ACTIVE → CANCELED / EXPIRED / TRIAL / TRIAL_EXPIRED), direct creation via `subscriptionCreate` vs quote-based creation, the nightly cron driving automated renewals / expirations / trial transitions, the `evergreen` auto-renew gate, explicit lifecycle mutations (`subscriptionCancel`, `subscriptionReinstate`, `subscriptionSetAutoRenew`, `subscriptionTrialExtend`, `subscriptionTrialConvert`), quantity updates (`subscriptionQuantityUpdate`), tenant metadata (`subscriptionTenantUpdate`), metered-usage reporting with `featureUsageCreate` / `featureUsageUpdate` / `featureUsageDelete` (requires `billing:w…
