Add New Gadget: C4 Explosive

Add a remotely detonated C4 explosive that can be placed or thrown by the player. The charge could stick to walls, floors, ceilings, vehicles, drones, and RC cars, allowing players to create traps or deliver explosives remotely. Players should be able to detonate the C4 at any time, including while it is still airborne. Its limited quantity and detonation range could be balanced to prevent it from becoming overly powerful.