Run retention pruning even when no new recordings are found

The early exit on zero DB results was bypassing the retention step.
Retention should run on every cycle regardless of new footage.

Author: tvancott42

scripts/backup.sh

@@ -218,7 +218,11 @@ EOSQL
 # Count results (subtract header line)
 TOTAL=$(echo "$CSV" | tail -n +2 | grep -c . || true)
 if [ "$TOTAL" -eq 0 ]; then
-    log "No new recordings found. Done."
+    log "No new recordings found."
+    if [ -n "${RETENTION_DAYS}" ] || [ -n "${RETENTION_PERCENT}" ]; then
+        run_retention_prune
+    fi
+    log "Done."
     exit 0
 fi
 log "Found ${TOTAL} recording file(s) to back up"