Late module publishes no longer roll back newer versions

The module registry can receive the same module from more than one release lane. A slower lane could finish after a newer release and make its older upload the active registry version simply because it arrived last. The next portal restart would then load the older module and silently undo the newer release.

The registry now compares versions before changing which one it serves. An older upload still lands, but a newer version whose files are present stays current. The older one is kept as its fallback when it is the better one, and stays downloadable at its own version. A newer version whose files have gone missing does not block recovery: the next valid upload replaces it. To go back to an older version on purpose, publish the fix under a higher version.