Add project files.

Gateway/Models/ProviderRequest.cs

@@ -0,0 +1,9 @@
+namespace Gateway.Models;
+
+public sealed class ProviderRequest
+{
+    public string Operation { get; set; } = string.Empty;
+    public string? TenantId { get; set; }
+    public string? RequestId { get; set; }
+    public Dictionary<string, object>? Payload { get; set; }
+}