Upgrading sweeps away plugin cache directories nothing uses, freeing disk space.
What's wrong with this entry?
Migrating the installed-plugins file now sweeps the plugin cache root and deletes cache directories no longer referenced by any installed plugin, reclaiming disk space left by earlier versions.
- Aware of WSL companion paths, so a directory still reachable through a different view of the same volume is not deleted.
- Cleanup is skipped entirely when the cache root volume cannot be read.
Cleaned up legacy cache directory:
Strings lifted out of the shipped bundle, so the claim above can be checked against them.