Add remaining project files

Models/AccountSetting.cs

@@ -0,0 +1,17 @@
+using LiteDB;
+
+namespace DeluxeBackend.Models
+{
+    public class AccountSetting
+    {
+        [BsonId]
+        public long Id { get; set; }
+
+        [BsonRef("accounts")]
+        public required Account Account { get; set; }
+
+        public required string Key { get; set; }
+        public required string Value { get; set; }
+
+    }
+}