Add refactored build menu functions

Introduces misc/build refactor_menu.func with comprehensive build and configuration functions for LXC containers in Proxmox VE. Refactors and modularizes initialization, storage selection, resource management, and advanced interactive configuration logic from misc/build.func.

misc/build.func

@@ -1803,8 +1803,12 @@ install_script() {
     menu_items+=("4" "Settings")
   fi
 
-  if [ -z "$CHOICE" ]; then
+  APPDEFAULTS_OPTION="$appdefaults_option"
+  SETTINGS_OPTION="$settings_option"
 
+  # Main menu loop - allows returning from Settings
+  while true; do
+    if [ -z "$CHOICE" ]; then
       TMP_CHOICE=$(whiptail \
         --backtitle "Proxmox VE Helper Scripts" \
         --title "Community-Scripts Options" \
@@ -1818,9 +1822,6 @@ install_script() {
       CHOICE="$TMP_CHOICE"
     fi
 
-  APPDEFAULTS_OPTION="$appdefaults_option"
-  SETTINGS_OPTION="$settings_option"
-
     # --- Main case ---
     local defaults_target=""
     local run_maybe_offer="no"
@@ -1833,10 +1834,10 @@ install_script() {
       base_settings "$VERBOSE"
       echo_default
       defaults_target="$(ensure_global_default_vars_file)"
+      break
       ;;
     2 | advanced | ADVANCED)
       header_info
-
       echo -e "${ADVANCED}${BOLD}${RD}Using Advanced Install on node $PVEHOST_NAME${CL}"
       echo -e "${INFO}${BOLD}${DGN}PVE Version ${PVEVERSION} (Kernel: ${KERNEL_VERSION})${CL}"
       METHOD="advanced"
@@ -1844,13 +1845,15 @@ install_script() {
       advanced_settings
       defaults_target="$(ensure_global_default_vars_file)"
       run_maybe_offer="yes"
+      break
       ;;
-  3 | mydefaults | MYDEFAULTS)
+    3 | mydefaults | MYDEFAULTS | userdefaults | USERDEFAULTS)
       default_var_settings || {
         msg_error "Failed to apply default.vars"
         exit 1
       }
       defaults_target="/usr/local/community-scripts/default.vars"
+      break
       ;;
     "$APPDEFAULTS_OPTION" | appdefaults | APPDEFAULTS)
       if [ -f "$(get_app_defaults_path)" ]; then
@@ -1861,6 +1864,7 @@ install_script() {
         _load_vars_file "$(get_app_defaults_path)"
         echo_default
         defaults_target="$(get_app_defaults_path)"
+        break
       else
         msg_error "No App Defaults available for ${APP}"
         exit 1
@@ -1868,15 +1872,16 @@ install_script() {
       ;;
     "$SETTINGS_OPTION" | settings | SETTINGS)
       settings_menu
-    # After settings menu, return to main menu
-    input_options
-    return
+      # After settings menu, show main menu again
+      header_info
+      CHOICE=""
       ;;
     *)
       echo -e "${CROSS}${RD}Invalid option: $CHOICE${CL}"
       exit 1
       ;;
     esac
+  done
 
   if [[ -n "$defaults_target" ]]; then
     ensure_storage_selection_for_vars_file "$defaults_target"