Package canonical eCPS benchmark certificate

[MaxGhenis]

Summary

• Package the canonical 2024 production eCPS benchmark manifest used for MP replacement gates.
• Make mp300k gates use that packaged manifest by default when no explicit --benchmark-manifest is supplied.
• Add regressions that the packaged manifest pins the 3,701-target production eCPS surface and that default gate execution uses it.

Tests

• env -u PYTHONPATH -u UV_FROZEN uv run --extra dev python -m pytest tests/pipelines/test_mp_benchmark_manifest.py tests/pipelines/test_mp300k_artifact_gates.py -q
• env -u PYTHONPATH -u UV_FROZEN uv run --extra dev ruff check src/microplex_us/pipelines/mp_benchmark_manifest.py src/microplex_us/pipelines/mp300k_artifact_gates.py tests/pipelines/test_mp_benchmark_manifest.py tests/pipelines/test_mp300k_artifact_gates.py
• env -u PYTHONPATH -u UV_FROZEN uv build --wheel --out-dir /tmp/microplex_us_canonical_ecps_manifest_wheel_check
• unzip -l /tmp/microplex_us_canonical_ecps_manifest_wheel_check/microplex_us-0.2.0-py3-none-any.whl | rg 'frozen_production_ecps_2024_benchmark_manifest.json'