fix: modify replay_npz.py compatibility with MotionLoader API

[masahiro-kubota]

Description

replay_npz.py was not compatible with the current MotionLoader API, so the replay script could not run.

Traceback (most recent call last):
  File "/mnt/ssd2/booster/booster_train/scripts/replay_npz.py", line 148, in <module>
    main()
  File "/mnt/ssd2/booster/booster_train/scripts/replay_npz.py", line 143, in main
    run_simulator(sim, scene)
  File "/mnt/ssd2/booster/booster_train/scripts/replay_npz.py", line 104, in run_simulator
    motion = MotionLoader(
             ^^^^^^^^^^^^^
TypeError: MotionLoader.__init__() missing 1 required positional argument: 'track_joint_names'

This PR updates replay_npz.py to pass the tracked body names and joint names expected by MotionLoader.

Test Performed

I verified locally that the reference motion can be replayed with:

python scripts/replay_npz.py \
  --motion ../booster_assets/motions/K1/k1_fight_001.npz \
  --device cuda:0