Get sandbox bank application status

Returns deterministic sandbox status metadata for a bank application when the authenticated automation client has banks.applications.read. External URL: /v1/banks/current/applications/{id}. Current Next.js implementation path: /api/platform/v1/banks/current/applications/[id]. This read-only route does not require Idempotency-Key; it returns application state, safe display labels, next-action metadata, document-manifest availability, redaction boundaries, and blocked side effects only and never exposes bank secrets, raw MyInfo, credit bureau data, bank statements, raw document contents, NRIC/FIN, income-proof contents, full financial profile data, signed storage URLs, callback signing secrets, provider calls, or enterprise ingress claims. Live bank applications remain unavailable until promotion gates have REST, consent, audit, sandbox, callback, and operations evidence. Bank pilot posture remains information/referral and pre-approval only, recommendation and live bank-decision claims remain deferred, and partner-status publication remains private-first.