standardize lerobot key

[yhnsu]

Description

This PR standardizes the LeRobot key naming conventions across the EmbodiChain project to align with the official LeRobot dataset format. The changes ensure consistency between the codebase, tests, and documentation.

Changes

Core Code Changes

embodichain/data/enum.py

• Added LeRobotKey enum class with all official LeRobot field keys:
  • OBS_STR, OBS_PREFIX, OBS_ENV_STATE, OBS_STATE, OBS_IMAGE, OBS_IMAGES
  • OBS_LANGUAGE, OBS_LANGUAGE_TOKENS, OBS_LANGUAGE_ATTENTION_MASK
  • OBS_LANGUAGE_SUBTASK, OBS_LANGUAGE_SUBTASK_TOKENS, OBS_LANGUAGE_SUBTASK_ATTENTION_MASK
  • ACTION, ACTION_PREFIX, ACTION_TOKENS, ACTION_TOKEN_MASK
  • REWARD, TRUNCATED, DONE, INFO

embodichain/lab/gym/envs/managers/datasets.py

• Replaced hardcoded string literals with LeRobotKey enum values:
  • observation.state instead of observation.qpos/qvel/qf for proprio state
  • observation.images.{sensor_name} instead of sensor_name.color for camera images
  • action for action data
  • observation.{key}.{sub_key} pattern for nested features

Key Changes

Before	After
observation.qpos	observation.state
observation.qvel	(removed - consolidated into state)
observation.qf	(removed - not in standard LeRobot format)
sensor_name.color	observation.images.{sensor_name}
Hardcoded strings	LeRobotKey enum references

Type of changes

• Bug fix (non-breaking change which fixes an issue)
• Enhancement (non-breaking change which improves an existing functionality)
• New feature (non-breaking change which adds functionality)
• Breaking change (existing functionality will not work without user modification)
• Documentation update

Checklist

• I have run the black . command to format the code base.
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• Dependencies have been updated, if applicable.