Add project files.

Gateway/Models/CreateCampaignRequest.cs

@@ -0,0 +1,17 @@
+namespace Gateway.Models;
+
+public class CreateCampaignRequest
+{
+    // Campaign name
+    public string Name { get; set; } = "";
+
+    // For Google: budget uses micros (1,000,000 micros = 1 currency unit)
+    // e.g. $50/day => 50_000_000 micros
+    public long DailyBudgetMicros { get; set; }
+
+    // Optional: for future (Search/Display/PMax)
+    public string ChannelType { get; set; } = "Search";
+
+    // Optional: where your UI can store draft settings
+    public Dictionary<string, string>? Meta { get; set; }
+}