fix: make issue 705 CI evidence portable

[TATP-233]

Summary

• 修复 feat: add manager-based mjwarp training infrastructure #847 真实 CI run 30698393464 暴露的 evidence ancestry 与 Python 版本可移植性问题。
• test-shard checkout 显式使用 fetch-depth: 0，并由 shard audit fail closed 锁定完整历史。
• Phase 4 host summary 仅允许 throughput 在 Python 3.11/3.13 间的 ULP 舍入差异；timing、count、memory 和字段集合仍严格相等。
• 从 clean source 重采集 Phase 4、legacy retirement 和 final A/B/C/D evidence，并 promotion canonical artifacts。

Closes #855
Part of #705

Failure Evidence

• Real run: https://github.com/unilabsim/UniLab/actions/runs/30698393464
• Source: 30d69111ebab8dab2743ea4d4299c3ff96c87fa3
• Ruff、mypy、pyright、Docs、shard A/B 成功；shard C/D 因 shallow checkout 无法证明 evidence ancestry，aggregate 按设计失败。
• Phase 4 在 Python 3.11 重算 Python 3.13 artifact 时只有 throughput 出现 3.64e-12 至 1.82e-11 的绝对浮点舍入差异。

Validation

• env LD_LIBRARY_PATH=/tmp/nvidia-570.133.07/usr/lib/x86_64-linux-gnu make test-all
• uv run scripts/audit_ci_test_shards.py
• uv run scripts/validate_issue705_final.py --json
• git diff --check
• 两轮代码审查

Results:

• Full gate: 2348 passed, 26 skipped, 449 deselected, 1 xfailed; coverage 68%; Ruff, mypy, pyright PASS.
• Benchmark smoke: module 36/37, script 37/38; only platform-optional MLX skipped.
• Standard shard equivalents: A 870 passed, B 551 passed, C 285 passed, D 636 passed; expected platform skips/deselects only.
• Shard audit: 4 shards / 227 test files / exactly 6 local_evidence nodes / 0 errors.
• Final validator: ok=true, 12 mandatory commands, A/B/C/D complete, promotion_required=true, errors=[].
• Head Actions runs / check-runs / check-suites / status contexts: all 0 before PR creation.
• Working tree clean.

Artifacts

• Phase 4 source: cd8c1733352487e156cd2941fe7e31733b42a64a
• Phase 4 SHA256: 7e412aebc093fc58875061fe3aa8c1c23d9e1493a800469dafce1c745acd0bc7
• Legacy retirement source: 8bcb11c3705fe0ea41bde29399b9c28798849433
• Legacy retirement SHA256: beb06b4e663d88f60bc8fa343b0dec13505a3f6036c7494717d13ec54f2a83e5
• Final source: 8bcb11c3705fe0ea41bde29399b9c28798849433
• Final SHA256: ee186e0e57325cfee4b3c384d7f4a219b72c15447a0028666d99f919aecdb887

Boundaries

• Base is the long-lived feat/issue-705-manager-mjwarp branch, not main.
• Coverage threshold remains 25%.
• Exact six-node local_evidence allowlist is unchanged.
• No mjwarp support, task, DR capability, or execution profile is expanded.
• mjwarp and mujoco remain independent physics backends.