s&box BanSystem: INetworkListener with LocalData Persistence

Implementing a ban system in s&box multiplayer requires handling connection filtering, persistence, and both connected and offline banning. Challenges include:

1. Blocking connections at the network level
2. Persisting bans across server restarts
3. Supporting both online and offline (by SteamID) banning
4. Permission checking for ban commands
5. Integration with chat notifications