Bug Report: Purging mint-themes-x unexpectedly deletes Mint-Y directories and breaks theme selection #543

Summary
​When uninstalling legacy theme packages (such as mint-themes-x or mint-themes-legacy) via APT, the physical directories for the modern Mint-Y themes are unexpectedly deleted. Furthermore, even after manually restoring these directories from a LiveCD environment, the themes remain unavailable for selection in the Cinnamon "Simplified settings" panel.
​Steps to Reproduce
​Install a standard Linux Mint Cinnamon edition.
​Run the following command to purge legacy assets:
sudo apt purge mint-themes-x mint-x-icons mint-themes-legacy mint-l-icons
​Check the /usr/share/themes/ directory.
​Observe that the Mint-Y related folders (e.g., Mint-Y-Blue, Mint-Y-Sand) have been deleted alongside the legacy themes.
​Manually restore the Mint-Y directories from a LiveCD to /usr/share/themes/.
​Open System Settings -> Themes and click on "Simplified settings...".
​Actual Result
​The Mint-Y physical theme files are deleted by the post-rm or dependency logic of the legacy packages.
​After manual restoration, Mint-Y still does not appear as a selectable option in the Simplified Settings UI, suggesting a broken index or hardcoded dependency on the now-missing legacy schemas.
​Expected Result
​The Mint-Y theme suite should be treated as a modern, independent entity. Purging legacy/obsolete themes (X and L series) should not impact the physical files or the usability of the current Mint-Y theme.
​Theme selection logic should be decoupled so that Mint-Y remains valid even if Mint-X is not present on the system.
​Environment Information
​OS: Linux Mint 22.3 (Cinnamon Edition)
​Cinnamon Version: 6.0+
​Affected Packages: mint-themes, mint-themes-x, mint-themes-legacy
​Technical Observation
​It appears that the mint-themes package structure treats these directories as shared or uses a cleanup script that is too aggressive. The fact that the UI (especially the Simplified panel) fails to recognize the themes even after file restoration indicates that there is a deep-seated metadata dependency on the Mint-X structure within the Cinnamon theme-selection logic.