chore(tools): add cheap-dim LIBERO-plus task list for native scale-up

Reference input for gen_liberoplus.py: 284 light+language perturbation tasks
(the asset-cheap dimensions — no new meshes, only small inline light scenes)
spread across object/goal/spatial/libero_10 base tasks. Lets a future run scale
the native libero_plus_native.* set beyond the committed representative 40
without touching the 6.4GB asset pack.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: geng-haoran