Add authentication for secure document access

Introduced a new login page (`Login.razor`) to handle user authentication via access codes. Implemented `AuthService` to validate access codes through an API. Updated `ReportViewer.razor` to check user access and redirect unauthorized users to the login page. Modified `Program.cs` to register `AuthService` for dependency injection. Enhanced document fetching in `ReportViewer.razor` to ensure secure access control.

EnvelopeGenerator.ReceiverUI/Pages/ReportViewer.razor

@@ -19,8 +19,10 @@
 @using EnvelopeGenerator.ReceiverUI.Options
 @inject IJSRuntime JSRuntime
 @inject IOptions<ApiOptions> AppOptions
+@inject NavigationManager Navigation
 @inject InMemoryReportStorageWebExtension ReportStorage
 @inject EnvelopeGenerator.ReceiverUI.Services.DocumentService DocumentService
+@inject EnvelopeGenerator.ReceiverUI.Services.AuthService AuthService
 
 <link href="_content/DevExpress.Blazor.Themes/blazing-berry.bs5.min.css" rel="stylesheet" />
 <link href="_content/DevExpress.Blazor.Reporting.Viewer/css/dx-blazor-reporting-components.bs5.css" rel="stylesheet" />
@@ -170,6 +172,14 @@
 
     protected override async Task OnInitializedAsync() {
 
+        if (!string.IsNullOrWhiteSpace(EnvelopeKey)) {
+            var hasAccess = await AuthService.CheckEnvelopeAccessAsync(EnvelopeKey);
+            if (!hasAccess) {
+                Navigation.NavigateTo($"/login/{Uri.EscapeDataString(EnvelopeKey)}");
+                return;
+            }
+        }
+
         if (!AppOptions.Value.ForceToUseFakeDocument && !string.IsNullOrWhiteSpace(EnvelopeKey)) {
             var (pdfBytes, _) = await DocumentService.GetDocumentAsync(EnvelopeKey);
             if (pdfBytes is { Length: > 0 }) {