Parse ForwardSpeed from UpdateMotion (0xF74C) InterpretedMotionState.
Feed server-echoed RunRate into the player's MotionInterpreter so
get_state_velocity produces the correct speed. Previously hardcoded
at 1.0 (4.0 m/s), now matches character's Run skill.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>