Initial commit: JDE Scoping Tool migration project

Set up repository with legacy .NET Framework 4.8 source (OLD/),
new .NET 10 Blazor solution (NEW/), OpenSpec specifications,
documentation, and project configuration.

NEW/src/JdeScoping.Api/Models/LoginRequest.cs

@@ -0,0 +1,21 @@
+using System.ComponentModel.DataAnnotations;
+
+namespace JdeScoping.Api.Models;
+
+/// <summary>
+/// Login request payload
+/// </summary>
+public class LoginRequest
+{
+    /// <summary>
+    /// Username for authentication
+    /// </summary>
+    [Required(ErrorMessage = "Username is required")]
+    public string Username { get; set; } = string.Empty;
+
+    /// <summary>
+    /// Password for authentication
+    /// </summary>
+    [Required(ErrorMessage = "Password is required")]
+    public string Password { get; set; } = string.Empty;
+}