fix: update metadata structure in RSS feed

app/controllers/rss_controller.rb

@@ -26,15 +26,15 @@ class RssController < ApplicationController
           content_html: "<p>#{art.description}</p>",
           date_published: art.created_at.iso8601,
           image: art.image.attached? ? rails_blob_url(art.webp_image.processed) : nil,
-          # 自定义字段
-          _weather: {
+          metadata: {
             country: art.city&.country&.name,
             city: art.city&.name,
             state: art.city&.state&.name,
             description: art.description,
             prompt: art.prompt,
             date: art.weather_date&.strftime("%Y-%m-%d"),
-            formattedDate: art.formatted_time(:all, true)
+            formattedDate: art.formatted_time(:all, true),
+            cityUrl: city_url(art.city)
           }
         }
       end