List budgets in the active scope

Returns the Budget records configured in the active scope, as rendered by the Budgets page on route load. Each budget carries its target scope label, reset period (MONTHLY|QUARTERLY|ANNUAL), the configured limit and current spent/forecast figures (integers in ten-thousandths of the subscription currency's unit), its status (ACTIVE or THRESHOLD_BREACHED once spend crosses 100% of the limit), the configured alert thresholds (percentages such as 50/80/100), the alert channel, the owning team and a 12-point spend history sparkline. Standard q/sort/order/page/pageSize controls apply; status and period narrow the collection. Validation: scopeId must be accessible to the caller (404 NOT_FOUND if unknown); status must be ACTIVE|THRESHOLD_BREACHED and period MONTHLY|QUARTERLY|ANNUAL when supplied; pagination bounds enforced — violations map to 422 VALIDATION_FAILED. Async & state: Synchronous read; no state change. Threshold breaches detected by the budget evaluator are pushed as resource.updated SSE frames (kind billing.budget, patch with status and spent). Errors: 401 unauthenticated; 403 caller lacks a billing-capable role on the scope; 404 unknown scopeId; 422 malformed query parameters; 500 read-model failure. Idempotency/Concurrency: Safe, cacheable; no idempotency key required.