fix(myTischtennis): improve error handling for Playwright login and account verification

- Enhanced error handling in MyTischtennisClient and MyTischtennisService to provide clearer feedback when browser executables are missing.
- Updated responses to include specific error messages and status codes, improving user guidance for setup requirements.
- Refactored MyTischtennisDialog and MyTischtennisAccount components to handle API response errors more effectively, ensuring robust login and account management processes.

backend/services/myTischtennisService.js

@@ -247,20 +247,25 @@ class MyTischtennisService {
           effectiveLoginResult = playwrightResult;
         } else {
           console.warn('[myTischtennisService.verifyLogin] Playwright-Fallback fehlgeschlagen:', playwrightResult.error);
+          const isSetupError = !!playwrightResult.requiresSetup || playwrightResult.status === 503;
           effectiveLoginResult = {
             success: false,
             error: playwrightResult.error || 'Playwright-Fallback fehlgeschlagen',
-            requiresCaptcha: true,
-            status: 400
+            requiresCaptcha: !isSetupError,
+            status: isSetupError ? 503 : 400
           };
         }
       } catch (playwrightError) {
         console.warn('[myTischtennisService.verifyLogin] Playwright-Fallback Exception:', playwrightError?.message || playwrightError);
+        const rawMessage = String(playwrightError?.message || playwrightError || '');
+        const isSetupError = /Executable doesn't exist|download new browsers|playwright install/i.test(rawMessage);
         effectiveLoginResult = {
           success: false,
-          error: `Playwright-Fallback Exception: ${playwrightError?.message || 'Unbekannter Fehler'}`,
-          requiresCaptcha: true,
-          status: 400
+          error: isSetupError
+            ? 'Playwright-Browser ist auf dem Server nicht installiert. Bitte "npx playwright install chromium" ausführen.'
+            : `Playwright-Fallback Exception: ${playwrightError?.message || 'Unbekannter Fehler'}`,
+          requiresCaptcha: !isSetupError,
+          status: isSetupError ? 503 : 400
         };
       }
     }