feat: add formatted date to RSS feed response

- Include formattedDate in the RSS feed response
- Utilize art.formatted_time method for better date formatting

This change enhances the RSS feed by providing a more user-friendly
formatted date alongside the existing weather date. This allows
clients consuming the RSS feed to display dates in a more readable
format, improving overall usability.

app/controllers/rss_controller.rb

@@ -33,7 +33,8 @@ class RssController < ApplicationController
             state: art.city&.state&.name,
             description: art.description,
             prompt: art.prompt,
-            date: art.weather_date&.strftime("%Y-%m-%d")
+            date: art.weather_date&.strftime("%Y-%m-%d"),
+            formattedDate: art.formatted_time(:all, true)
           }
         }
       end