- Move ECC setup guide reference from README to claude-code-tools.md
- Add CLAUDE.md with mandatory README sync rule
- Add "Last updated" date to README
- README is now a clean index of repo contents
Separate AST Index into its own Skills section, add descriptions
for both extension mechanisms, and fix markdown lint warnings.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>