curl --request GET \
  --url https://api.agentic.scope3.com/api/v2/buyer/campaigns/{campaignId} \
  --header 'Authorization: Bearer <token>'

{
  "campaign": {
    "campaignId": "cmp_987654321",
    "advertiserId": "12345",
    "name": "Summer 2025 Campaign",
    "status": "DRAFT",
    "createdAt": "2025-01-15T10:30:00Z",
    "updatedAt": "2025-01-20T14:45:00Z",
    "brief": "<string>",
    "flightDates": {
      "startDate": "2025-01-15T00:00:00Z",
      "endDate": "2025-03-31T23:59:59Z"
    },
    "budget": {
      "total": 1,
      "currency": "USD",
      "dailyCap": 1,
      "pacing": "EVEN"
    },
    "constraints": {
      "channels": [
        "<string>"
      ],
      "countries": [
        "<string>"
      ]
    },
    "performanceConfig": {
      "optimizationGoal": {
        "eventSourceId": "es_abc123",
        "eventType": "page_view",
        "targetRoas": 4,
        "targetCpa": 25,
        "attributionWindow": {
          "clickThrough": "7d",
          "viewThrough": "1d"
        }
      }
    },
    "productCount": 15
  }
}