Add public benchmark entry point and reusable evaluation contracts

[stevezkw1998]

Summary

• add a portable neorepro benchmark predictions.csv one-file entry point
• report leakage-filtered common support, pooled metrics, tie-aware patient Top-K metrics, patient bootstrap intervals, paired differences, random ranking and available strata
• add machine-readable JSON and Markdown outputs, a two-predictor synthetic example and public contract documentation
• retain the standalone frozen-benchmark audit, reusable dataset/predictor contracts, RCC extension and multilingual README synchronization
• merge current v0.1.1 author and Zenodo DOI metadata from main

Validation

• ruff check src tests
• pytest -q — 54 passed
• clean Python 3.11 wheel install and CLI smoke test
• all seven localized READMEs synchronized

The PR remains a draft pending final CI confirmation.