CI Fixes and Code Quality Improvements

This release fixes all remaining CI linting errors (130 → 0) and ensures
the CI workflow passes. All changes maintain numerical parity with the
reference GSW implementation.

Key improvements:
- Removed duplicate function definitions and dead code
- Fixed all linting errors (F811, F821, B904, E722, E402)
- Added SAAR data extraction script for test infrastructure
- Fixed configuration issues (mypy.ini)
- All 29 parity tests pass
- No numerical regressions detected
