Use specific exit codes in VM scripts

Replace generic exit 1 with distinct exit codes across vm/*.sh to make failures more actionable for callers. Changes include: use 226 for missing imported-disk references, 237 for pv installation failures, 115 for download/extract/ISO-related failures, 214 for insufficient disk space during FreeBSD decompression, and 119 for missing storage detection. Updated scripts: archlinux-vm.sh, docker-vm.sh, haos-vm.sh, openwrt-vm.sh, opnsense-vm.sh, truenas-vm.sh, umbrel-os-vm.sh.

vm/opnsense-vm.sh

@@ -616,7 +616,7 @@ for ver in $RELEASE_LIST; do
 done
 if [ -z "$URL" ]; then
   msg_error "Could not find generic FreeBSD amd64 qcow2 image (non-UFS/ZFS)."
-  exit 1
+  exit 115
 fi
 msg_ok "Download URL: ${CL}${BL}${URL}${CL}"
 
@@ -626,7 +626,7 @@ if ! check_disk_space "$TEMP_DIR" 20; then
   msg_error "Insufficient disk space in temporary directory ($TEMP_DIR)."
   msg_error "Available: ${AVAILABLE_GB}, Required: ~20GB for FreeBSD image decompression."
   msg_error "Please free up space or ensure /tmp has sufficient storage."
-  exit 1
+  exit 214
 fi
 
 msg_info "Downloading FreeBSD Image"
@@ -639,7 +639,7 @@ if ! check_disk_space "$TEMP_DIR" 15; then
   AVAILABLE_GB=$(df -h "$TEMP_DIR" | awk 'NR==2 {print $4}')
   msg_error "Insufficient disk space for decompression."
   msg_error "Available: ${AVAILABLE_GB}, Required: ~15GB for decompressed image."
-  exit 1
+  exit 214
 fi
 
 msg_info "Decompressing FreeBSD Image (this may take a few minutes)"
@@ -648,7 +648,7 @@ if ! unxz -cv $(basename $URL) >${FILE}; then
   msg_error "Failed to decompress FreeBSD image."
   msg_error "This is usually caused by insufficient disk space."
   df -h "$TEMP_DIR"
-  exit 1
+  exit 115
 fi
 
 # Remove the compressed file to save space