curl --request POST \
  --url https://api.useplinth.com/sandbox/create

{
  "object": "sandbox",
  "tenant_id": "ten_01JXYZ...",
  "api_key": "sk_test_a1b2c3d4e5f6...",
  "expires_at": "2026-06-19T12:00:00Z",
  "plans": [
    {
      "id": "pln_01JAA...",
      "name": "Starter",
      "amount_minor": "200000",
      "currency": "NGN",
      "interval": "month"
    },
    {
      "id": "pln_01JAB...",
      "name": "Pro",
      "amount_minor": "500000",
      "currency": "NGN",
      "interval": "month"
    },
    {
      "id": "pln_01JAC...",
      "name": "Max",
      "amount_minor": "1200000",
      "currency": "NGN",
      "interval": "month"
    }
  ],
  "customer": {
    "id": "cus_01JAD...",
    "name": "Sandbox Customer",
    "email": "customer@sandbox.ng"
  }
}