Upgrades remove the old Anthias images they replace

Every upgrade pulls a fresh image for each Anthias service, and until now it left the previous ones on the card. The installer's cleanup only removed untagged layers, so the old tagged images stayed, and a device that had upgraded a handful of times carried several full copies of Anthias. One person who asked for a fix found the last 6 releases taking about 16 GB on their devices. Removing them took the cards from 76% full to 26%.

From Anthias 2026.09.0, the installer and bin/upgrade_containers.sh remove the old images as their last step, once the new containers are running. If the pull or the start fails, the old images stay in place to fall back on.

Only Anthias images are removed (ghcr.io/screenly/anthias-*, plus the older screenly/anthias-* and screenly/srly-ose-* names), and only those no container uses, running or stopped. Tagged images for other containers you run on the same machine are left alone. Untagged leftovers, which nothing can use, are pruned as the installer already did. Each removal is printed as "Reclaimed superseded image" followed by the image name, and a device with nothing to clean prints nothing.

To clear the leftovers from earlier releases without waiting for the next upgrade, run ~/anthias/bin/purge_stale_images.sh. It's safe to run at any time.