chore: migrate license to Apache-2.0 — HybridRAG-eval

[qte77]

Summary

Migrate qte77/HybridRAG-eval license to Apache-2.0 (currently BSD).

Cannot push/create issues on that repo from current token — tracking here instead.

Steps

1. Replace LICENSE.md with canonical Apache 2.0 text (GitHub template)
2. Copyright line: Copyright 2026 qte77
3. Include APPENDIX section

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[qte77]

Refresher: qte77/HybridRAG-eval LICENSE is still BSD-3-Clause as of 2026-04-27. Migration to Apache-2.0 still pending.