feat: add admin user frontend contract

myteamwallet_frontend_modern/src/app/features/team-select/team-select.html

@@ -11,8 +11,8 @@
     <h1>Team auswählen</h1>
     <mat-nav-list>
       @for (player of players(); track player.id) {
-        <a mat-list-item [routerLink]="['/team', player.team?.id, 'overview']">
-          <span matListItemTitle>{{ player.team?.name }}</span>
+        <a mat-list-item [routerLink]="['/team', player.team.id, 'overview']">
+          <span matListItemTitle>{{ player.team.name }}</span>
           <span matListItemLine>{{ player.firstName }} {{ player.lastName }}</span>
         </a>
       }