Add remaining project files

Models/RefreshToken.cs

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+using LiteDB;
+using static DeluxeBackend.Enums;
+
+namespace DeluxeBackend.Models
+{
+    public class RefreshToken
+    {
+        [BsonId]
+        public long Id { get; set; }
+
+        public required string Token { get; set; }
+        public required DateTime Expires { get; set; }
+        public bool IsRevoked { get; set; } = false;
+
+        [BsonRef("accounts")]
+        public required Account Account { get; set; }
+    }
+}