List read-only invoice refund dispute gates

Returns invoice refund/dispute gates for all platform launch verticals when the authenticated automation client has platform.billing_owner_visibility.read. External URL: /v1/providers/current/invoice-refund-dispute-gates. Current Next.js implementation path: /api/platform/v1/providers/current/invoice-refund-dispute-gates. This read-only route does not require Idempotency-Key; it exposes payment-collection completion, refund-policy, dispute-policy, processor-refund contract, chargeback-policy, support-owner, customer-notice, and audit prerequisites; blocked refund, dispute, chargeback, provider-call, payment, quota, and credential side effects; hidden payment-method, refund-receipt, and dispute-evidence payload posture; and next operator actions only. It never reads usage event tables or partner-facing billing tables, returns raw usage payloads, raw payment payloads, payment method payloads, refund receipt payloads, dispute evidence payloads, chargeback payloads, or processor payloads, sends invoices, records delivery receipts, collects payments, mutates refunds or disputes, enforces quota, suspends credentials, or calls external finance providers.