fix: prune dangling images after docker_update.sh pulls

docker_update_remaining.sh already pruned; docker_update.sh (daily)
did not — orphaned images accumulated with every daily update run.
Same prune pattern as docker_update_remaining.sh.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Docker_Essentials/docker_update.sh

@@ -311,6 +311,18 @@ for container in "${TARGET_CONTAINERS[@]}"; do
 
 done
 
+# ── Prune dangling images ─────────────────────────────────────────────────────
+# Old images become dangling after a pull lands a new digest. Prune here so
+# they don't accumulate across daily runs.
+if [[ "$DRY_RUN" == true ]]; then
+    warn "DRY RUN — would prune dangling images"
+    PRUNED_SUMMARY="(dry run)"
+else
+    PRUNED_OUTPUT=$(docker image prune -f 2>&1)
+    [[ "$ENABLE_LOGGING" == "true" ]] && echo "$PRUNED_OUTPUT" | sed 's/^/  /'
+    PRUNED_SUMMARY=$(echo "$PRUNED_OUTPUT" | grep -E "^Total reclaimed" || echo "nothing reclaimed")
+fi
+
 END=$(date +%s)
 
 # ==============================================================================================
@@ -330,6 +342,7 @@ fi
 [[ ${#UP_TO_DATE[@]} -gt 0 ]] && log "$ICON_RUNNING    Up to date:  ${#UP_TO_DATE[@]}"
 [[ ${#SKIPPED[@]} -gt 0 ]]    && log "$ICON_WARN       Skipped:     ${#SKIPPED[@]}"
 [[ ${#FAILED[@]} -gt 0 ]]     && echo "$ICON_ERROR      Failed:      ${FAILED[*]}"
+echo "$ICON_SYNC       Pruned:      ${PRUNED_SUMMARY:-none}"
 
 if [[ "$DRY_RUN" == true ]]; then
     warn "DRY RUN — no images pulled"