feat(update-scripts): replace whiptail with msg_menu for unattended updates

Remove all whiptail dialogs from ct update_script() functions and replace
with msg_menu() - a lightweight read-based menu that supports:
- PHS_SILENT=1: auto-selects first (default) option for unattended mode
- Interactive: numbered menu with 10s timeout and default fallback

Converted scripts (whiptail menu → msg_menu):
- plex.sh, npmplus.sh, cronicle.sh, meilisearch.sh, node-red.sh
- homeassistant.sh, podman-homeassistant.sh
- vaultwarden.sh, alpine-vaultwarden.sh
- loki.sh, alpine-loki.sh
- alpine-grafana.sh, alpine-redis.sh, alpine-valkey.sh
- alpine-nextcloud.sh

Simplified scripts (removed unnecessary whiptail for single-action updates):
- alpine.sh, alpine-docker.sh, alpine-zigbee2mqtt.sh

Special handling:
- gitea-mirror.sh: replaced yesno/msgbox with read -rp confirmations,
  exit 75 in silent mode for major version upgrades requiring interaction
- vaultwarden.sh/alpine-vaultwarden.sh: passwordbox replaced with
  read -r -s -p, skipped in silent mode with warning
- nginxproxymanager.sh: exit 1 → exit 75 for disabled script

Infrastructure:
- Added msg_menu() helper to misc/build.func
- Added exit code 75 handling in update-apps.sh (skip, not fail)

Closes #11620

ct/npmplus.sh

@@ -20,10 +20,9 @@ color
 catch_errors
 
 function update_script() {
-  UPD=$(whiptail --backtitle "Proxmox VE Helper Scripts" --title "UPDATE MODE" --radiolist --cancel-button Exit-Script "Spacebar = Select" 14 60 2 \
-    "1" "Check for Alpine Updates" OFF \
-    "2" "Update NPMplus Docker Container" ON \
-    3>&1 1>&2 2>&3)
+  UPD=$(msg_menu "NPMplus Update Options" \
+    "1" "Check for Alpine Updates" \
+    "2" "Update NPMplus Docker Container")
 
   header_info "$APP"