fix: Erweitere Playwright-Konfiguration für mehr Browser-Unterstützung

backend/playwright.config.mjs

@@ -23,5 +23,17 @@ export default defineConfig({
         ...devices['Desktop Chrome'],
       },
     },
+    {
+      name: 'firefox',
+      use: {
+        ...devices['Desktop Firefox'],
+      },
+    },
+    {
+      name: 'webkit',
+      use: {
+        ...devices['Desktop Safari'],
+      },
+    },
   ],
 });