v3.2.3: vc-update runs adaptive migration on version-equal installs

Fixes vc-update skipping adaptive content migration when the installed version already matches the remote. install.sh writes .vc-version to the new version but cannot run the adaptive legacy-layout migration; vc-update would then bail with 'Already up to date', stranding legacy reports/references dirs and flat plans. vc-update now runs a legacy-artifact scan on version equality and continues to Part D migration when legacy artifacts exist.