Add devise

app/views/layouts/application.html.erb

@@ -11,6 +11,16 @@
   </head>
 
   <body>
+    <p class="notice"><%= notice %></p>
+    <p class="alert"><%= alert %></p>
+    <div style="display: block;">
+      <% if user_signed_in? %>
+        <p>Welcome <%= current_user.username %></p>
+        <%= link_to "Sign Out", destroy_user_session_path, data: { turbo_method: :delete } %>
+      <% else %>
+        <%= link_to "Sign In", new_user_session_path %>
+        <%= link_to "Register", new_user_registration_path %>
+      <% end %>
     <%= yield %>
   </body>
 </html>