Ten images built, none pushed: the guard checks free space against every
profile before doing anything, but a push uploads what already exists and
needs no disk. It now measures only what actually has to be BUILT — and
says so when there is nothing to build — so a full disk can no longer
turn 'publish' into a no-op.

It also asks docker where its root dir is rather than assuming
/var/lib/docker, which on this machine is /storage/docker.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0182DhR1eFNPQyGmDrpHbedY