CivitCreator to record, add computed ProfileUrl

StabilityMatrix.Core/Models/Api/CivitCreator.cs

@@ -2,11 +2,14 @@
 
 namespace StabilityMatrix.Core.Models.Api;
 
-public class CivitCreator
+public record CivitCreator
 {
     [JsonPropertyName("username")]
-    public string Username { get; set; }
+    public string? Username { get; init; }
 
     [JsonPropertyName("image")]
-    public string? Image { get; set; }
+    public string? Image { get; init; }
+
+    [JsonIgnore]
+    public string? ProfileUrl => Username is null ? null : $"https://civitai.com/user/{Username}";
 }