fix: handle user creation failure

- Add @user.destroy to ensure proper cleanup on failure

This change prevents incomplete user records from being left in the database when user creation fails due to an error.

app/controllers/users_controller.rb

@@ -35,6 +35,7 @@ class UsersController < ApplicationController
       rescue => e
         logger.error "User creation failed: #{e.message}"
         flash[:danger] = "Something went wrong. Please try again."
+        @user.destroy
         render "new", status: :unprocessable_entity
       end
     else