GET /api/merchants

POST /api/merchants

{
  "name": "Acme Corp",
  "legalName": "Acme Corporation LLC",
  "email": "billing@acme.com",
  "phone": "+1 555-0100",
  "website": "https://acme.com",
  "industry": "Technology"
}

GET /api/merchants/:id

PATCH /api/merchants/:id

DELETE /api/merchants/:id

{
  "retention": "immediate"
}

POST /api/nmi/test-connection

{
  "apiKey": "your_private_key",
  "gatewayUrl": "https://secure.nmi.com"
}

POST /api/nmi/credentials

{
  "merchantId": "clx...",
  "name": "Production Gateway",
  "apiKey": "your_private_key",
  "tokenizationKey": "your_tokenization_key",
  "gatewayUrl": "https://secure.nmi.com"
}

POST /api/nmi/sync

{
  "nmiAccountId": "clx..."
}