Update AuthController to use specific auth scheme

The `[Authorize]` attribute on the `Check` method was updated to specify the `AuthScheme.Sender` authentication scheme. This change ensures that the `Check` endpoint now requires authentication using this specific scheme, enhancing security and supporting multiple authentication schemes within the application.

EnvelopeGenerator.API/Controllers/AuthController.cs

@@ -69,7 +69,7 @@ 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()