fix: update created_at timestamp display

- Change displayed time from weather_date to created_at in
  cities and weather arts show templates. This ensures that the
  time shown reflects when the record was created instead of the
  weather date which may not be accurate for representation.

app/views/cities/show.html.erb

@@ -107,7 +107,7 @@
                     <div class="flex items-center justify-between text-white">
                       <div class="text-2xl font-bold"><%= art.temperature %>°C</div>
                       <div class="text-right">
-                        <div class="font-medium"><%= art.weather_date.strftime("%H:%M") %></div>
+                        <div class="font-medium"><%= art.created_at.strftime("%H:%M") %></div>
                         <div class="text-sm opacity-80"><%= art.weather_date.strftime("%B %d, %Y") %></div>
                       </div>
                     </div>

app/views/weather_arts/show.html.erb

@@ -56,7 +56,7 @@
                   <%= @weather_art.weather_date.strftime("%B %d, %Y") %>
                 </div>
                 <div class="badge badge-lg badge-secondary">
-                  <%= @weather_art.weather_date.strftime("%H:%M") %>
+                  <%= @weather_art.created_at.strftime("%H:%M") %>
                 </div>
               </div>