feat: add contract-generated harness skill

[MiaoDX]

Summary

This PR ships the contract-first harness work and keeps the CI demo surfaces working with the new generated project harness skill path.

• Adds Python-authored harness contract generation under src/roboharness/contract/.
• Generates the agent-skill/roboharness-harness/ artifact set from the contract.
• Adds bounded visual review package support for MuJoCo/G1 proof surfaces.
• Localizes MuJoCo approval and contract logic around the maintained grasp wedge.
• Keeps G1/SONIC demo imports and native LeRobot typing compatible after optional demo dependencies are installed.

Test Coverage

• Contract generator, visual review, CLI, MuJoCo wedge, G1 WBC review, and LeRobot adapter paths are covered by new or existing tests.
• Repository coverage after full suite: 91.88%.

Pre-Landing Review

No blocking issues found in the ship checklist pass. No SQL/DB writes, shell execution, frontend files, or prompt files are changed in this diff.

Demo Compatibility

All previous CI demo surfaces were verified locally:

• MuJoCo grasp report
• G1 WBC reach report
• LeRobot G1 locomotion report
• Native LeRobot GR00T report
• Native LeRobot SONIC report
• SONIC locomotion report
• SONIC tracking report

Native LeRobot demos were validated in a Python 3.12 CI-like environment. Local Python 3.13 cannot import unitree_sdk2py because of a CycloneDDS runtime symbol boundary, while CI uses Python 3.12.

Verification Results

• uv run python scripts/validate_demo_matrix.py
• PYTHONPATH=src python3 -m roboharness.cli contract check agent-skill/roboharness-harness/contract.py --output-dir agent-skill/roboharness-harness
• uv run ruff check .
• uv run ruff format --check .
• uv run mypy src/
• MUJOCO_GL=osmesa uv run pytest -q -> 570 passed, 3 skipped, coverage 91.88%

Test plan

• Demo matrix validates all 7 demos
• Generated harness skill contract is current
• Ruff check passes
• Ruff format check passes
• Mypy passes
• Full pytest suite passes with MuJoCo headless rendering

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