What's New in 2.0:
- 99.9% Test Pass Rate (1391 tests)
- DECY-220: Fixed malloc cast expression handling
- Portable tests using CARGO_MANIFEST_DIR
- System include discovery for stdlib.h, string.h
- Performance improvements

Updated:
- Workspace version: 1.0.2 → 2.0.0
- All internal dependencies to 2.0.0
- README.md with 2.0 features and crates.io badge
- Book documentation with updated installation

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>