Archive retained source update trees safely

[HANCORE-linux]

Summary

• keep eight active source-update rollback trees and atomically move the oldest tree into a bounded private archive before staging
• validate exact tree names, ownership, modes, symlinks, special files, per-tree and aggregate bounds, devices, mounts, and directory identities before archival
• preserve archived trees without automatic deletion and offer the archive separately during interactive uninstall with No as the default
• report an actionable archive path when all 56 archive slots are occupied and document manual maintenance

Validation

• make test
• python3 tests/source-update.py (50 tests)
• tests/uninstall.sh
• python3 -m py_compile scripts/update-omaq.py tests/source-update.py
• shellcheck scripts/update-omaq.sh scripts/uninstall-omaq.sh tests/uninstall.sh
• omarchy plugin validate .
• git diff --check

GitHub checks are not claimed by these local results.