feat: add additional columns to city dashboards

- Add '图像个数' column to show the count of weather arts.
- Add '最后更新时间' column to display the last weather fetch time.

These additions enhance the information displayed in the Ahoy Dashboard and
Cities admin panel, providing more context for each city.

app/admin/ahoy_dashboard.rb

@@ -47,6 +47,8 @@ ActiveAdmin.register_page "Ahoy Dashboard" do
             column("访问量") { |city| city.view_count }
             column("状态") { |city| status_tag(city.active? ? "活跃" : "停用") }
             column("所属区域") { |city| city.country.name+"/"+city.country.region.name }
+            column("图像个数") { |city| city.weather_arts.count }
+            column("最后更新时间") { |city| city.last_weather_fetch }
             # column("状态") { |city| status_tag(city.active? ? "活跃" : "停用") }
             column("操作") { |city|
               button_to "停用",
@@ -67,6 +69,8 @@ ActiveAdmin.register_page "Ahoy Dashboard" do
             column("访问量") { |city| city.view_count }
             column("状态") { |city| status_tag(city.active? ? "活跃" : "停用") }
             column("所属区域") { |city| city.country.name+"/"+city.country.region.name }
+            column("图像个数") { |city| city.weather_arts.count }
+            column("最后更新时间") { |city| city.last_weather_fetch }
             column("操作") { |city|
               button_to "激活",
                         admin_ahoy_dashboard_toggle_city_status_path(city_id: city.id),

app/admin/cities.rb

@@ -32,6 +32,8 @@ ActiveAdmin.register City do
     column :latitude
     column :longitude
     column :active
+    column("图像个数") { |city| city.weather_arts.count }
+    column("最后更新时间") { |city| city.last_weather_fetch }
     actions
   end