Enhance MyTischtennisService and MyTischtennisAccount.vue for improved login handling and account status display

Updated MyTischtennisService to include federation nickname in account data and refined login logic to utilize stored passwords or valid sessions more effectively. Enhanced error handling for login failures. In MyTischtennisAccount.vue, added account status management to display password storage status and improved account loading logic to fetch both account and status data concurrently.

frontend/src/views/MyTischtennisAccount.vue

@@ -16,7 +16,7 @@
           
           <div class="info-row">
             <label>Passwort gespeichert:</label>
-            <span>{{ account.savePassword ? 'Ja' : 'Nein' }}</span>
+            <span>{{ accountStatus && accountStatus.hasPassword ? 'Ja' : 'Nein' }}</span>
           </div>
           
           <div class="info-row" v-if="account.clubId">
@@ -195,6 +195,7 @@ export default {
       loading: true,
       loadingStats: false,
       account: null,
+      accountStatus: null,
       latestFetches: null,
       showDialog: false,
       showHistoryDialog: false
@@ -240,10 +241,16 @@ export default {
     async loadAccount() {
       try {
         this.loading = true;
-        const response = await apiClient.get('/mytischtennis/account');
-        this.account = response.data.account;
+        const [accountResponse, statusResponse] = await Promise.all([
+          apiClient.get('/mytischtennis/account'),
+          apiClient.get('/mytischtennis/status')
+        ]);
+        this.account = accountResponse.data.account;
+        this.accountStatus = statusResponse.data;
       } catch (error) {
         console.error('Fehler beim Laden des Accounts:', error);
+        this.account = null;
+        this.accountStatus = null;
         this.$store.dispatch('showMessage', {
           text: 'Fehler beim Laden des myTischtennis-Accounts',
           type: 'error'
@@ -292,6 +299,9 @@ export default {
         if (error.response?.status === 400 && message.includes('Kein Passwort gespeichert')) {
           // Passwort-Dialog öffnen
           this.showDialog = true;
+          this.showInfo('Passwort benötigt', message, '', 'warning');
+        } else {
+          this.showInfo('Login fehlgeschlagen', message, '', 'error');
         }
         
         this.$store.dispatch('showMessage', {
@@ -314,6 +324,7 @@ export default {
       try {
         await apiClient.delete('/mytischtennis/account');
         this.account = null;
+        this.accountStatus = null;
         this.showInfo('Erfolg', 'myTischtennis-Account erfolgreich getrennt', '', 'success');
       } catch (error) {
         console.error('Fehler beim Löschen des Accounts:', error);