kazoo43/VOTTURS-ZCITY-FIXED ? reverse-engineered prompt

I want you to clean up and rebuild this Garry’s Mod Lua gamemode so it stays true to Vottur’s ZCity, but is much more stable and easier to maintain.

Please organize the code into clear client, server, and shared parts, remove dead or duplicated logic, and make the loading order reliable. Focus on fixing performance problems, especially anything that runs every frame when it does not need to, and reduce unnecessary network traffic by only sending data when something actually changes. Also make the inventory, weapon handling, entity cleanup, and UI behave consistently and stop common bugs like nil errors, duplicate spawning, timer leaks, and broken references.

Keep the same overall gameplay feel and features, just make everything smoother, faster, and safer. If you need current Garry’s Mod Lua docs or best practices, look them up online first.