Ported progress from SPA and began scaffolding Identity UI.

Laid some groundwork in backend.

Began customizing Identity UI.

Props/Models/User/ApplicationPreferences.cs

@@ -0,0 +1,15 @@
+using System.ComponentModel.DataAnnotations;
+
+namespace Props.Shared.Models.User
+{
+    public class ApplicationPreferences
+    {
+        public int Id { get; set; }
+
+        [Required]
+        public string ApplicationUserId { get; set; }
+
+        public bool EnableSearchHistory { get; set; } = true;
+        public bool DarkMode { get; set; } = false;
+    }
+}