Refactored endpoints to be more functional and more expressive

PostFundManagement.Domain/Errors/NotFoundError.cs

@@ -0,0 +1,14 @@
+namespace PostFundManagement.Domain.Errors;
+
+public sealed class NotFoundError : Error
+{
+    public static NotFoundError New { get; } = new();
+
+    public NotFoundError() : base(string.Empty) { }
+
+    public NotFoundError(string Message) : base(Message) { }
+
+    public static NotFoundError Create() => new();
+
+    public static NotFoundError Create(string message) => new(message);
+}