Add notification feature to backup scripts for various services

Enhance backup scripts for Nextcloud, Gitea, Paperless, Vaultwarden, Immich, and VPS configurations by adding Telegram notifications upon completion. Include details such as backup size and objects backed up. Update backup documentation to reflect these changes and ensure clarity on backup processes and retention policies.

scripts/backup-etc-pve.sh

@@ -21,3 +21,12 @@ chmod 600 "$BACKUP_ROOT"/etc-pve-*.tar.gz "$BACKUP_ROOT"/etc-host-configs-*.tar.
 
 find "$BACKUP_ROOT" -name 'etc-pve-*.tar.gz' -mtime +$RETENTION_DAYS -delete
 find "$BACKUP_ROOT" -name 'etc-host-configs-*.tar.gz' -mtime +$RETENTION_DAYS -delete
+
+NOTIFY_SCRIPT="${NOTIFY_SCRIPT:-/root/scripts/notify-telegram.sh}"
+if [ -x "$NOTIFY_SCRIPT" ]; then
+  SIZE=$(du -sh "$BACKUP_ROOT" 2>/dev/null | cut -f1) || true
+  BODY="Резервное копирование завершено.
+Объекты: архивы /etc/pve, конфиги сети (interfaces, hosts, resolv.conf).
+Размер копии: ${SIZE:-—}."
+  "$NOTIFY_SCRIPT" "⚙️ Конфиги хоста" "$BODY" || true
+fi