s&box: Player movement with CharacterController — Accelerate, Move, IsOnGround, Punch

In s&box, player movement uses CharacterController (for kinematic, collision-constrained movement) not Rigidbody. Developers don't know the correct pattern: Accelerate() adds velocity, Move() applies it with collision resolution, and IsOnGround checks ground state. Calling Move() without Accelerate() first does nothing useful.