feat(application): enforce validation and API error mapping rules

src/core/DigitalData.TaskFlow.Application/Common/Exceptions/InvalidRequestApiException.cs

@@ -0,0 +1,18 @@
+using DigitalData.TaskFlow.Domain.Enums;
+
+namespace DigitalData.TaskFlow.Application.Common.Exceptions;
+
+/// <summary>
+/// Represents a 400 API exception.
+/// </summary>
+public sealed class InvalidRequestApiException : ApiException
+{
+    /// <summary>
+    /// Initializes a new instance of the <see cref="InvalidRequestApiException"/> class.
+    /// </summary>
+    /// <param name="message">Response message.</param>
+    public InvalidRequestApiException(string message)
+        : base(400, MetaCode.InvalidRequest, message)
+    {
+    }
+}