Fix solo mode finish screen: use isSoloMode flag instead of broken myId.startsWith check

Fix lap counting: complete lap on last checkpoint (not start line), fix multiplayer finish

Fix finish screen not showing in Solo Practice mode

Fix bugs: arch direction, track edge collisions, floating signs, stand orientation, gravel planes

Complete F1-style circuit overhaul: track layout, car mesh, daylight environment, and F1 branding

Fix lap counter prematurely jumping to Lap 2 at race start

Fix camera position to be behind the car instead of in front, fixing reversed controls

Fix mobile controls pointer-events and touchcancel bugs

Add mobile on-screen controls for small screens

Initial game commit