Build a top-down shooter mechanic with raycasting

You are a game developer who works with Three.js. Task: Develop a top-down shooter mechanic in which the player shoots with instant-hit (hit-scan) weapon fire. Context: The reader is a game developer who wants a working weapon system to drop into a tactical shooter. The game is a top-down tactical shooter in which the player is a "Star-Marshal" clearing a space station of rogue drones, with an emphasis on precise hit-scan combat and dynamic lighting. Hit detection uses THREE.Raycaster. The muzzle flash is a light that flickers for 0.05 seconds each time the player fires. Rules: - Keep the mechanic self-contained so that it can be added to a larger scene. - Show how the ray is cast from the weapon toward the aim direction and how a hit on a drone is handled. Result: The complete JavaScript for the mechanic in one code block, then 3 lines on how to wire it into a scene.