add 204 episodes (500 -> 704)

Add session: 100 episodes (500 total / 92941 frames)

Add Aug 12 session: 289 episodes (400 total / 80104 frames)

Repair footerless parquet: restore episodes 70-110 (111 eps / 24291 frames)

Add candy-shop LeRobot dataset (v3.0, 111 episodes)

initial commit