curl -X GET "https://api.adrelay.dev/v1/campaigns?platform=google_ads&status=ACTIVE&limit=25" \
  -H "X-API-Key: $ADRELAY_API_KEY"

{
  "unified": [
    {
      "id": "camp_abc123",
      "platform": "google_ads",
      "remote_id": "123456789",
      "name": "Summer Sale 2026",
      "status": "ACTIVE",
      "goal": "CONVERSIONS",
      "budget_amount": 50.00,
      "budget_period": "DAILY",
      "currency": "USD",
      "created_at": "2026-03-01T12:00:00Z",
      "updated_at": "2026-03-15T08:30:00Z"
    }
  ],
  "pagination": {
    "next_cursor": "eyJpZCI6ImNhbXBfYWJjMTIzIn0=",
    "has_more": true
  }
}