feat(database): add migration and sync-db scripts to deployment process

- Introduced a new npm script for database migrations in package.json.
- Updated update-backend.sh to execute migrations and conditionally run legacy sync-db based on environment variable.
- Enhanced syncDatabase.js to skip initialization routines if APP_INIT_ON_START is not set, promoting best practices for schema changes during deployment.

backend/utils/syncDatabase.js

@@ -77,6 +77,13 @@ import initializeWidgetTypes from './initializeWidgetTypes.js';
 // Normale Synchronisation (nur bei STAGE=dev Schema-Updates)
 const syncDatabase = async () => {
     try {
+        const runInitOnStart = process.env.APP_INIT_ON_START === '1';
+        if (!runInitOnStart) {
+            console.log('⏭️  APP_INIT_ON_START!=1: Überspringe datenbankseitige Initialisierungs-/Ensure-Routinen beim Start.');
+            console.log('💡 Empfehlung: Schema-Änderungen via Migrationen im Deploy ausführen (npm run db:migrate).');
+            return;
+        }
+
         // Zeige den aktuellen Stage an
         const currentStage = process.env.STAGE || 'nicht gesetzt';
         console.log(`🚀 Starte Datenbank-Synchronisation (Stage: ${currentStage})`);