Work: Complete per-step observation noise coverage for Sharpa hand in-hand envs #306

Background

Issue #125 mixed multiple robots into one work item. This issue now tracks the Sharpa hand slice only. Allegro is no longer in scope for this tracking set.

Current Repo Audit

• SharpaInhandRotation already injects joint observation noise in src/unilab/envs/manipulation/sharpa_inhand/rotation.py.
• SharpaInhandRotationGrasp inherits from SharpaInhandRotationEnv, so the shared observation path should be covered as one robot slice.
• I did not find dedicated Sharpa obs-noise tests in tests/.

Remaining Work

• Confirm both Sharpa in-hand env variants apply per-step observation noise through the shared observation path.
• Add dedicated unit tests for positive-noise and zero-noise cases.
• Record the validation command/result in the PR.

Definition of Done

• Sharpa in-hand envs have explicit per-step obs-noise coverage in tests
• Validation command is listed in the PR
• PR links back to Tracking: Per-robot per-step observation noise rollout #125

Scope

• Robot: Sharpa hand
• Includes: SharpaInhandRotation, SharpaInhandRotationGrasp
• Excludes: G1 / Go1 / Go2 / Allegro