serverWalkSpeed_ and serverSwimSpeed_ were stored in GameHandler but
never exposed or synced to the camera controller. The controller used
hardcoded WOW_WALK_SPEED and speed*SWIM_SPEED_FACTOR regardless of
server-sent speed changes.
Add getServerWalkSpeed()/getServerSwimSpeed() accessors, walkSpeedOverride_
and swimSpeedOverride_ fields in CameraController, and sync all three
server speeds each frame. Both swim speed sites (main and camera-collision
path) now use the override when set. This makes Slow debuffs (walk speed),
Swim Form, and Engineering fins actually affect movement speed.