- Bump version from v0.3.0 to v0.3.1 in MASTER_INDEX.md (April 13, 2026)
- Update docs/README.md version from 6.0 to 6.1 with test cleanup focus
- Update production ready status date from March 18 to April 13, 2026
- Add v0.3.1 release section with milestone tracking fix and test cleanup achievements
- Document removal of 12 legacy test files and conftest consolidation
- Add migration notes for legacy
