fix(heimdall): migrate PHP to 8.4 on update (#15767)

Legacy Debian 12 containers still had PHP 8.2 while Heimdall v2.8.1 requires PHP ^8.4. Run setup_php during update and use shared backup helpers for database and public data.

ct/heimdall-dashboard.sh

@@ -35,14 +35,12 @@ function update_script() {
     sleep 1
     msg_ok "Stopped Service"
 
-    msg_info "Backing up Data"
-    cp -R /opt/Heimdall/database database-backup
-    cp -R /opt/Heimdall/public public-backup
-    sleep 1
-    msg_ok "Backed up Data"
-
+    create_backup /opt/Heimdall/database \
+                  /opt/Heimdall/public
+    PHP_VERSION="8.4" PHP_FPM="YES" setup_php
     setup_composer
     fetch_and_deploy_gh_release "Heimdall" "linuxserver/Heimdall" "tarball"
+    restore_backup
 
     msg_info "Updating Heimdall-Dashboard"
     cd /opt/Heimdall
@@ -50,18 +48,6 @@ function update_script() {
     $STD composer dump-autoload
     msg_ok "Updated Heimdall-Dashboard"
 
-    msg_info "Restoring Data"
-    cd ~
-    cp -R database-backup/* /opt/Heimdall/database
-    cp -R public-backup/* /opt/Heimdall/public
-    sleep 1
-    msg_ok "Restored Data"
-
-    msg_info "Cleaning Up"
-    rm -rf {public-backup,database-backup}
-    sleep 1
-    msg_ok "Cleaned Up"
-
     msg_info "Starting Service"
     systemctl start heimdall.service
     sleep 2