Refactor account card title and layout styles for improved UI consistency

src/Duempelkas.App/Components/Accounts/AccountCard.razor

@@ -2,7 +2,7 @@
 
 <div class="card account-card h-100" @onclick="Navigate">
     <div class="card-body d-flex flex-column justify-content-between">
-        <h5 class="card-title mb-3">@Account.Name</h5>
+        <h3 class="card-title mb-3 mt-0">@Account.Name</h3>
         <div class="@(Account.TotalBalance >= 0 ? "amount-positive" : "amount-negative") fs-4">
             @($"{Account.TotalBalance:N2} €")
         </div>

src/Duempelkas.App/Components/Layout/MainLayout.razor

@@ -5,7 +5,6 @@
         <a class="navbar-brand" href="">
             <strong>Dümpelkas</strong> <small class="text-muted">Kassenbuch</small>
         </a>
-        <span class="version-label">v@(AppVersion)</span>
     </nav>
 
     <main class="flex-grow-1 overflow-auto p-3">