Engine update

Build Update

- Major engine update: Project upgraded to Unreal Engine 5.6 (from 5.5).
Based on Epic’s notes, general improvements are expected. After some local testing, indirect lighting appears to perform better. Please report any issues you encounter.

- Weapon selection logic updated: Now uses mouse wheel to select weapons. Grenades can be selected when activated.

- Level art: Additional visual work in progress across the map.

- FSR temporarily removed:
Apologies — AMD has not yet provided an official plugin for FSR compatibility with UE5.6. It will be re-enabled as soon as it becomes available.