Move probe_deepseek to src package, drop stale scripts/ copy
src/probe_deepseek.py adds quantization support (--bits 4/8/16),
integrates with src.data.load_records/TEST_SPLITS and src.eval.normalize.
pyproject.toml entrypoint already pointed here.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>