Use Result.ToActionResult in RefreshController

Import the API extensions and replace manual result handling in RefreshController with result.ToActionResult(), removing the inline empty-token check and switch-based error mapping. Also normalize the empty-token error message in UserSessionRefresher from "cannot be empty" to "can't be empty". This centralizes Result -> IActionResult conversion and simplifies the controller logic.

Govor.Application/Users/UserSessions/UserSessionRefresher.cs

@@ -34,7 +34,7 @@ public class UserSessionRefresher : IUserSessionRefresher
     {
         if (string.IsNullOrWhiteSpace(refreshToken))
         {
-            return Result.Failure<RefreshResult>(Error.Failure("Auth.EmptyToken", "Refresh token cannot be empty."));
+            return Result.Failure<RefreshResult>(Error.Failure("Auth.EmptyToken", "Refresh token can't be empty."));
         }
         
         var hashedToken = _jwtTokenHasher.HashToken(refreshToken);