CJK fixtures and tests already exist from previous work:
- tests/fixtures/cjk/ contains all 4 required PDFs
- Ground truth files for each encoding (GB18030, Shift-JIS, EUC-KR, Big5)
- Tests in crates/pdftract-core/tests/cjk_encoding.rs and tests/test_encoding.rs
- Tests fail due to unimplemented CJK encoding (expected for Phase 2.3)
- Updated PROVENANCE.md with CJK fixture entries
Fixtures are ready for CJK encoding implementation.
Closes bf-3ourh
