Fix range verifier grading for out-of-range predictions

[mitre88]

Summary

• Fix range_verifier grading when a prediction falls outside the target range.
• Add coverage for lower-bound, in-range, upper-bound, and out-of-range predictions.
• Configure pytest to include the repository root so local test runs work without manually setting PYTHONPATH.

Root cause

_grade_range_verifier only initialized grade_type for correct predictions. Out-of-range predictions left grade_type undefined and raised UnboundLocalError instead of returning an incorrect grade.

Validation

• uv run --extra dev pytest tests/test_utils.py tests/test_zeroshot.py -q
• uv run --extra dev pytest -q
• git diff --check

/claim https://algora.io/PrimeIntellect-ai/bounties/ihUsQETKr8S5vBRu