Improve model synchronization in sequelize.js by temporarily removing associations to prevent automatic foreign key creation. Add logging for association management during the sync process, ensuring clarity in model handling.

backend/utils/sequelize.js

@@ -476,10 +476,28 @@ const syncModelsAlways = async (models) => {
             }
             
             try {
-                // constraints: false verhindert, dass Sequelize Foreign Keys automatisch erstellt
+                // constraints: false wird von Sequelize ignoriert wenn Associations vorhanden sind
-                // Foreign Keys sollten nur über Migrations verwaltet werden
+                // Wir müssen die Associations temporär entfernen, um Foreign Keys zu verhindern
+                const originalAssociations = model.associations ? { ...model.associations } : {};
+                const associationKeys = Object.keys(originalAssociations);
+                
+                // Entferne temporär alle Associations, damit Sequelize keine Foreign Keys erstellt
+                if (associationKeys.length > 0) {
+                    console.log(`  ⚠️  Temporarily removing ${associationKeys.length} associations from ${model.name} to prevent FK creation`);
+                    // Lösche alle Associations temporär
+                    for (const key of associationKeys) {
+                        delete model.associations[key];
+                    }
+                }
+                
                 console.log(`  🔄 Syncing model ${model.name} with constraints: false`);
                 await model.sync({ alter: true, force: false, constraints: false });
+                
+                // Stelle die Associations wieder her
+                if (associationKeys.length > 0) {
+                    console.log(`  ✅ Restoring ${associationKeys.length} associations for ${model.name}`);
+                    model.associations = originalAssociations;
+                }
             } finally {
                 // Restore VIRTUAL fields after sync
                 for (const [key, attr] of Object.entries(virtualFields)) {