fix(eval): check last line for LLM judge verdict in fuzzy_match and ua_match

[AUTHENSOR]

Summary

llm_fuzzy_match and llm_ua_match in evaluation_harness/helper_functions.py extract the judge verdict by checking whether substrings like "correct", "incorrect", "same", or "different" appear anywhere in the judge response. When the judge reasons before its final verdict (common for GPT-4), the reasoning text can contain these words, causing the wrong verdict to be selected.

Example: a judge response like "The student's phrasing differs but is not incorrect. The answer is correct." matches "incorrect" first (via the substring scan over the full text), returning 0.0 when the verdict should be 1.0.

Additionally, both functions used assert "correct" in response / assert "same" in response, which crashes the benchmark if the judge uses a synonym the harness does not expect (e.g., "wrong" or "not matching").

Fix

• Check only the last line of the judge response for the verdict token, so reasoning text does not override the judge's concluding statement.
• Replace assert with a fail-safe return 0.0 when no recognized verdict token is found.

Verification

• Diff touches only llm_fuzzy_match and llm_ua_match (14 lines changed).
• Both functions now bind the verdict to the judge's last line, matching the convention used by other eval frameworks (e.g., inspect_ai, openai/evals cot_classify).
• The assert crash path is eliminated.