RoboLab v0.3.0

Added

• Explicit coordinate-frame contract: end-effector observations are now
  published in the robot-root frame, with a compatibility shim for older
  recordings (robolab/core/logging/frame_compat.py) and a reference doc
  (docs/frames.md).
• Ground-truth state export during stepping: --enable-gt-state makes every
  runner emit a raw per-env world-state snapshot each step under
  obs["gt_state"] (robolab.eval.GroundTruthStateExporter; schema in
  docs/environment_run.md).
• VoLo policy backend (policies/volo/): a proxy wrapper over existing
  clients that adds depth observations, camera calibration, and ground-truth
  state metadata to the inference payload.
• Robot-owned scene fixtures with per-robot fixture selection
  (robolab/core/environments/scene_fixture.py): a robot config declares the
  table fixture it is mounted on (or none, for robots with their own base),
  and the environment factory swaps the task scene's default fixture
  accordingly.
• Multi-gripper support in the task conditional system: robots can declare
  named gripper groups (e.g. "gripper": ["left", "right"] on a bimanual
  robot), and success/failure predicates can target any member of a group or
  require several grippers simultaneously (see docs/task_conditionals.md
  and docs/event_tracking.md).
• Pull request template and documentation of accepted PR types in
  CONTRIBUTING.md.
• News section in the README and an ecosystem page (docs/ecosystem.md).

Fixed

• Explicitly-named tasks now resolve correctly from scoped content-pack
  folders.