style: improve sign out button layout

- Add padding and flex layout to the sign out button
- Wrap the icon and text in a div for better structure

These changes update the sign out button in the navbar for improved
accessibility and aesthetics, aligning it better with the overall UI
style.

app/views/layouts/_navbar.html.erb

@@ -62,11 +62,13 @@
             <li>
               <%= button_to destroy_user_session_path,
                             method: :delete,
-                            class: "w-full text-left" do %>
+                            class: "flex items-center gap-2 w-full p-2" do %>
+                <div class="flex items-center gap-2">
                   <svg xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="1.5" stroke="currentColor" class="w-4 h-4">
                     <path stroke-linecap="round" stroke-linejoin="round" d="M15.75 9V5.25A2.25 2.25 0 0013.5 3h-6a2.25 2.25 0 00-2.25 2.25v13.5A2.25 2.25 0 007.5 21h6a2.25 2.25 0 002.25-2.25V15M12 9l-3 3m0 0l3 3m-3-3h12.75" />
                   </svg>
-                Sign out
+                  <span>Sign out</span>
+                </div>
               <% end %>
             </li>
           <% else %>