List read-only current provider invoice dry runs

Returns invoice dry-run previews for all platform launch verticals when the authenticated automation client has platform.billing_owner_visibility.read. External URL: /v1/providers/current/invoice-dry-runs. Current Next.js implementation path: /api/platform/v1/providers/current/invoice-dry-runs. This read-only route does not require Idempotency-Key; it exposes deterministic invoice draft previews, approved rollup line items, and manual-review posture 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.