curl --request GET \
  --url https://api.interchange.io/api/v2/buyer/campaigns \
  --header 'Authorization: Bearer <token>'

{
  "campaigns": [
    {
      "campaignId": "cmp_987654321",
      "advertiserId": "12345",
      "name": "Summer 2025 Campaign",
      "createdAt": "2025-01-15T10:30:00Z",
      "updatedAt": "2025-01-20T14:45:00Z",
      "flightDates": {
        "startDate": "2025-01-15T00:00:00Z",
        "endDate": "2025-03-31T23:59:59Z"
      },
      "constraints": {
        "geo_countries": [
          "<string>"
        ],
        "geo_countries_exclude": [
          "<string>"
        ],
        "geo_regions": [
          "<string>"
        ],
        "geo_regions_exclude": [
          "<string>"
        ],
        "geo_metros": [
          {
            "system": "nielsen_dma",
            "values": [
              "<string>"
            ]
          }
        ],
        "geo_metros_exclude": [
          {
            "system": "nielsen_dma",
            "values": [
              "<string>"
            ]
          }
        ],
        "geo_postal_areas": [
          {
            "country": "<string>",
            "system": "postal_code",
            "values": [
              "<string>"
            ]
          }
        ],
        "geo_postal_areas_exclude": [
          {
            "country": "<string>",
            "system": "postal_code",
            "values": [
              "<string>"
            ]
          }
        ],
        "language": [
          "<string>"
        ],
        "device_platform": [
          "ios"
        ],
        "device_type": [
          "desktop"
        ],
        "device_type_exclude": [
          "desktop"
        ],
        "channels": [
          "<string>"
        ],
        "countries": [
          "<string>"
        ]
      },
      "productCount": 15,
      "budget": {
        "total": 1,
        "currency": "USD"
      }
    }
  ],
  "total": 42
}