Fix AnswerBench algebra-036 CSV alignment

[ctkrug]

Summary

• close the unterminated Problem field for imo-bench-algebra-036
• restore $Y(x)=A+\frac{B}{x}-x$ to the Short Answer column
• leave every other byte in answerbench_v2.csv unchanged

Fixes #13.

Root cause

The multiline problem statement was missing its closing CSV quote, so the answer and remaining metadata were parsed as five fields instead of the six columns declared by the header.

Validation

• Python's standard-library CSV reader parses all 400 data records with exactly six fields.
• imo-bench-algebra-036 has the expected short answer, category, subcategory, and source.
• A separate byte-level checker confirms the candidate differs from current main by exactly one inserted 0x22 byte.
• The repaired file has SHA-256 0c05a0d4af9cbe3e70413b250d6c9cac1bfe4d848f6c196f83ed61ebef9ced16.

The reproducible validation packet is available at https://proofs.charliekrug.com/publications/deepmind-superhuman-13-answerbench-column-20260722-170424-418499/.

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[ctkrug]

@googlebot rescan