Update billing config

curl -X PUT https://api.interchange.io/api/v2/storefront/billing \
  -H "Authorization: Bearer $SCOPE3_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "platformFeePercent": 12.5,
    "fees": [
      { "name": "Ad serving", "description": "Third-party ad serving", "feePercent": 2 }
    ],
    "currency": "USD",
    "defaultNetDays": 30
  }'

{
  "billing": {
    "onboardingStatus": "complete",
    "platformFeePercent": 12.5,
    "fees": [
      { "name": "Ad serving", "description": "Third-party ad serving", "feePercent": 2 }
    ],
    "currency": "USD",
    "country": "US",
    "defaultNetDays": 30,
    "payoutDetails": {
      "beneficiaryName": "Meridian Media Group Inc.",
      "addressLine1": "500 Harbor Blvd",
      "addressLine2": null,
      "city": "Seattle",
      "region": "WA",
      "postalCode": "98101",
      "countryCode": "US",
      "accountNumberLast4": "6789",
      "bankIdentifierType": "FEDWIRE_ABA",
      "bankIdentifierValue": "021000021",
      "completedAt": "2026-07-01T09:30:00Z"
    },
    "inherited": false,
    "createdAt": "2026-04-25T12:00:00Z",
    "updatedAt": "2026-05-01T09:30:00Z"
  }
}