Refine authorization and rendering mechanisms

Updated `EnvelopeSenderPage.razor` to replace the `[Authorize]`
attribute with the `@rendermode InteractiveWebAssembly` directive,
indicating a shift in how authorization or rendering is handled.

Modified the `Check` method in `AuthController.cs` to specify
`AuthenticationSchemes = AuthScheme.Sender` in the `[Authorize]`
attribute, enforcing a more specific authentication scheme for
this endpoint.

EnvelopeGenerator.Server/EnvelopeGenerator.Server.Client/Pages/EnvelopeSenderPage.razor

@@ -1,6 +1,5 @@
 @page "/sender"
-@attribute [Microsoft.AspNetCore.Authorization.Authorize(Policy = "Sender")]
-
+@rendermode InteractiveWebAssembly
 @using System.Text.Json
 @using EnvelopeGenerator.Domain.Constants
 @using EnvelopeGenerator.Server.Client.Models

EnvelopeGenerator.Server/EnvelopeGenerator.Server/Controllers/AuthController.cs

@@ -63,7 +63,7 @@ public partial class AuthController(IOptions<AuthTokenKeys> authTokenKeyOptions,
     [ProducesResponseType(typeof(void), StatusCodes.Status200OK)]
     [ProducesResponseType(typeof(void), StatusCodes.Status401Unauthorized)]
     [HttpGet("check")]
-    [Authorize]
+    [Authorize(AuthenticationSchemes = AuthScheme.Sender)]
     public IActionResult Check(string? role = null)
         => role is not null && !User.IsInRole(role)
             ? Unauthorized()