Refactor culture initialization logic

Moved culture initialization from App.razor to Program.cs to ensure culture settings are applied before the app starts. Removed CultureService injection and OnInitializedAsync method from App.razor. Updated LanguageSelector.razor to change language without page reload, enhancing user experience. Added System.Globalization to Program.cs for culture support.

EnvelopeGenerator.ReceiverUI/App.razor

@@ -1,6 +1,4 @@
 @using System.Globalization
-@using EnvelopeGenerator.ReceiverUI.Services
-@inject CultureService CultureService
 
 <Router AppAssembly="@typeof(Program).Assembly">
     <Found Context="routeData">
@@ -12,12 +10,3 @@
         </LayoutView>
     </NotFound>
 </Router>
-
-@code {
-    protected override async Task OnInitializedAsync()
-    {
-        var culture = await CultureService.InitializeCultureAsync();
-        CultureInfo.DefaultThreadCurrentCulture = culture;
-        CultureInfo.DefaultThreadCurrentUICulture = culture;
-    }
-}