List fiat payment capabilities

GET /api/payment-capabilities

curl -sS "$AGENTBANK_BASE_URL/api/payment-capabilities"

{
  "capabilities": [
    {
      "fiat_currency": "VND",
      "routes": [
        {
          "direction": "off_ramp",
          "supported_payment_instruments": ["bank_transfer", "qr"],
          "recipient_requirements": [
            {
              "payment_instrument": "bank_transfer",
              "country": "VN",
              "required_fields": ["country", "bank_name", "account_number", "holder_name"]
            },
            {
              "payment_instrument": "qr",
              "country": "VN",
              "required_fields": ["qr_content"]
            }
          ]
        },
        {
          "direction": "on_ramp"
        }
      ]
    }
  ]
}