feat: rebase static IP on gateway change

setup_cups.sh

@@ -1196,6 +1196,7 @@ install_watchdogs() {
     local current_interface=$(get_interface)
     local current_netmask=$(get_netmask)
     local current_dns=$(get_dns)
+    local current_host_octet="${current_ip##*.}"
     current_dns="${current_dns:-114.114.114.114 223.5.5.5}"
 
     local ping_targets="223.5.5.5 114.114.114.114"
@@ -1213,9 +1214,12 @@ STATIC_IP="$current_ip"
 STATIC_PREFIX="$current_netmask"
 STATIC_GATEWAY="$current_gateway"
 STATIC_DNS="$current_dns"
+STATIC_HOST_OCTET="$current_host_octet"
 PING_TARGETS="$ping_targets"
 FAIL_THRESHOLD=3
 DHCP_AFTER_FAILURE=1
+REBASE_STATIC_ON_GATEWAY_CHANGE=1
+REBASE_WAIT_SECONDS=20
 LOG_FILE="/var/log/cups-watchdog/network.log"
 MAX_LOG_SIZE_KB=256
 EOF