* Extended functionalities

* Added different UIs

MealPlan.Api/Extensions/ClaimsPrincipalExtensions.cs

@@ -0,0 +1,27 @@
+using System.Security.Claims;
+using Microsoft.AspNetCore.Mvc;
+
+namespace MealPlan.Api.Extensions;
+
+public static class ClaimsPrincipalExtensions
+{
+    public static Guid? GetUserId(this ClaimsPrincipal user)
+    {
+        var raw = user.FindFirstValue(ClaimTypes.NameIdentifier)
+                  ?? user.FindFirstValue("sub");
+        return Guid.TryParse(raw, out var id) ? id : null;
+    }
+
+    public static IActionResult? RequireUserId(this ClaimsPrincipal user, out Guid userId)
+    {
+        var id = user.GetUserId();
+        if (id is null)
+        {
+            userId = Guid.Empty;
+            return new UnauthorizedResult();
+        }
+
+        userId = id.Value;
+        return null;
+    }
+}