List read-only current provider usage summaries

Returns customer-visible usage summaries for all platform launch verticals when the authenticated automation client has platform.billing_owner_visibility.read. External URL: /v1/providers/current/usage-summary. Current Next.js implementation path: /api/platform/v1/providers/current/usage-summary. This read-only route does not require Idempotency-Key; it exposes plan state, usage-summary test IDs, approved rollup posture, and observe-only billing side-effect blocking only. It never reads usage event tables or partner-facing billing tables, returns raw usage payloads or raw payment payloads, sends invoices, collects payments, enforces quota, suspends credentials, or calls external finance providers.