Refactor: allow pre-setting variables before execution in install script (#1578)

* refactor: improve readability and structure of installation prompts in KlipperScreen-install.sh

* refactor: streamline user prompt and normalize input for NetworkManager installation

scripts/KlipperScreen-install.sh

@@ -41,6 +41,7 @@ install_graphical_backend()
       echo_text ""
       echo "Press enter for default (Xserver)"
       read -r -e -p "Backend Xserver or Wayland (cage)? [X/w]" BACKEND
+    fi
     if [[ "$BACKEND" =~ ^[wW]$ ]]; then
         echo_text "Installing Wayland Cage Kiosk"
         if sudo apt install -y $CAGE; then
@@ -63,7 +64,6 @@ install_graphical_backend()
             exit 1
         fi
     fi
-    fi
   done
 }
 
@@ -293,6 +293,8 @@ install_network_manager()
     if [ -z "$NETWORK" ]; then
         echo "Press enter for default (Yes)"
         read -r -e -p "Install NetworkManager for the network panel [Y/n]" NETWORK
+    fi
+    
     if [[ $NETWORK =~ ^[nN]$ ]]; then
         echo_error "Not installing NetworkManager for the network panel"
     else
@@ -313,7 +315,6 @@ EOF
         sync
         systemctl reboot
     fi
-    fi
 }
 
 # Script start
@@ -331,18 +332,20 @@ if [ -z "$SERVICE" ]; then
     echo_text ""
     echo "Press enter for default (Yes)"
     read -r -e -p "[Y/n]" SERVICE
-    if [[ $SERVICE =~ ^[nN]$ ]]; then
+fi
+
+if [[ $SERVICE =~ ^[nN]$ ]]; then
     echo_text "Not installing the service"
     echo_text "The graphical backend will NOT be installed"
-    else
+else
     install_graphical_backend
     install_systemd_service
     if [ -z "$START" ]; then
         START=1
     fi
-    fi
 fi
 
+
 install_packages
 create_virtualenv
 create_policy