chore: automate approved drift fact merges

[NocodeMrLi]

Summary

• turn scheduled drift audit out of shadow mode for apply-ready verdicts
• add a facts-only drift proposal applier guarded by audit summaries
• fix shared-URL proposal generation so each rule updates only its own fact id

Verification

• python3 -m unittest discover -s tests -q
• python3 scripts/validate_suite.py .
• python3 scripts/check_i18n_readme_structure.py .
• python3 scripts/scan_sensitive_content.py . --format json
• export_public_package.py + verify_public_package.py