ci: prune docker images before AND after deploy, not only on pull failure (#129)

The 2026-09-12 deploy of #126 failed instantly -- git pull on the VM hit 'No space left on device' before the deploy script could even capture a rollback target. Every deploy leaves 3 freshly SHA-tagged images that only got cleaned up by a prune gated on a failed compose pull; a failure earlier than that (like this one) never reached it. 96 of 100 local images were unreferenced, 23.76GB reclaimable, disk at 100%.

Move an unconditional docker image prune -af to the top of the deploy, before git pull, and upgrade the post-up -d prune from -f (dangling only) to -af (all unused) so stale tagged images stop re-accumulating. Both are safe: prune -a never touches an image a running container references.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

Claude-Session: https://claude.ai/code/session_01Tbknwttzou4s46PAykmtix

.gitea/workflows/deploy.yml

@@ -97,6 +97,21 @@ jobs:
           set -e
           cd /opt/drb
 
+          # server-26#129: every deploy pushes 3 freshly SHA-tagged images and
+          # nothing ever removed the old ones except a prune that only ran
+          # AFTER a successful `compose pull` -- so a run that never got that
+          # far (this one) left the leak unaddressed forever. That silently
+          # filled the disk to 100% over ~week of deploys (2026-09-12: 29G/29G
+          # used, 96 of 100 local images unreferenced, 23.76GB reclaimable) and
+          # took `git pull` itself down with "No space left on device" before
+          # the deploy could even determine a rollback target. Prune BEFORE
+          # doing anything else, not after: `docker image prune -af` only
+          # removes images with no container referencing them, so it can never
+          # touch what's currently running -- there is nothing here for a
+          # mid-flight deploy to lose. Warn-not-fail: a prune failure must not
+          # block a deploy that doesn't actually need the space this time.
+          docker image prune -af || echo "WARNING: pre-deploy image prune failed (server-26#129) -- disk pressure may persist"
+
           # Update compose files + mosquitto config
           git pull origin main
 
@@ -159,7 +174,12 @@ jobs:
             $COMPOSE pull
           fi
           $COMPOSE up -d --remove-orphans
-          docker image prune -f
+          # server-26#129: -f alone only removes dangling (untagged) images --
+          # the SHA-tagged image from every PAST deploy is not dangling, just
+          # unreferenced once `up -d` swaps the running container to the new
+          # tag, so it survived this indefinitely. -a catches those too; see
+          # the pre-pull prune above for why this can't touch anything live.
+          docker image prune -af
           ENDSSH
           )
           echo "$OUTPUT"