chore: rename signe to tabula-rasa across all files

chore: remove planning files and add .gitignore for public release

docs(phase-09): complete phase execution and verification

docs(09-02): complete README and user guide plan

feat(09-02): create docs/guide.md user guide with all modes documented

feat(09-02): create README.md with install instructions and mode overview

docs(09-01): complete repo restructure and install script plan

feat(09-01): create install.sh with conflict detection and backup

feat(09-01): restructure repo with synced agent files at top level

docs(09): create phase plan for packaging and documentation

docs(state): record phase 9 context session

docs(09): capture phase context

docs(phase-08): complete phase execution and verification

docs(08-02): complete project-scoped persona and reset plan

docs(08-01): complete setup skill and onboarding agent plan