feat(Core): update DTOs and shared models

FinlyticCore/Models/Auth/RegisterRequestDto.cs

@@ -0,0 +1,22 @@
+namespace FinlyticCore.Models.Auth;
+
+/// <summary>
+/// DTO representing a request for self-registration by a new user.
+/// </summary>
+public class RegisterRequestDto
+{
+    /// <summary>
+    /// User email address.
+    /// </summary>
+    public string Email { get; set; } = string.Empty;
+
+    /// <summary>
+    /// User plain-text password.
+    /// </summary>
+    public string Password { get; set; } = string.Empty;
+
+    /// <summary>
+    /// User full name.
+    /// </summary>
+    public string FullName { get; set; } = string.Empty;
+}