fix: content loading & fix: window index field lookup

[SocialMoods]

This PR fixes the content loading delay issue and issue when Player class has been changed during PlayerCreationEvent:

Minecraft.2026.09.13.-.11.31.01.01.mp4

    @EventHandler
    public void onPlayerCreation(PlayerCreationEvent event) {
        // inject proxy to handleDataPacket method
        event.setPlayerClass(SyncPlayer.class);
    }

public class SyncPlayer extends Player 

[KoshakMineDEV]

LGTM