[TF2] Fix - sync demoman HUD eye glow with decapitation count

[SanyaKor]

Summary

Fixes the Demoman eye glow in the HUD player model not updating with the decapitation count and remaining visible after respawn.

Previously, the effect was refreshed indirectly when touching a resupply cabinet because resupply rebuilt the HUD player model. Respawning reset the server-side decapitation count to 0, but did not trigger the same HUD refresh.

The HUD now checks the decapitation count in CTFHudPlayerClass::OnThink() and sets bForceEyeUpdate whenever the value changes. For this check, a new value stores the previously observed number of decapitations.

The previous decapitation count value is initialized to 0 because the player starts with no heads. If the HUD also needs to force refresh when the current value is initially 0, the previous count can be initialized to -1 instead . On respawn, the count changes from the number of collected heads back to 0, forcing the HUD to remove the green eye effect without requiring resupply.

Demo

• Before the fix: YouTube demo
• After the fix: YouTube demo