1. User requests KYC link
   → Backend creates Sumsub applicant
   → Returns verification URL

2. User completes identity verification on Sumsub
   → Submits documents, selfie, etc.

3. Sumsub sends webhook to Stableyard
   → POST /webhooks/kyc-update

4. Backend updates KYC status on account
   → approved: fiat settlement unlocked
   → rejected: user can retry

{
  "kyc": {
    "isActive": false,
    "status": "none",
    "applicantId": null,
    "activatedAt": null
  }
}