Implemented api key crud and started adding system page. Added 404 page

Moonlight.ApiServer/Database/Entities/ApiKey.cs

@@ -0,0 +1,11 @@
+namespace Moonlight.ApiServer.Database.Entities;
+
+public class ApiKey
+{
+    public int Id { get; set; }
+
+    public string Secret { get; set; }
+    public string Description { get; set; }
+    public string PermissionsJson { get; set; } = "[]";
+    public DateTime ExpiresAt { get; set; }
+}