feat: add city ranking panel to dashboard

- Implement a new panel in the Ahoy Dashboard
- Display least popular active cities along with their visit counts
- Include action buttons to toggle city statuses with confirmations

This addition enhances the admin dashboard by providing insights into
city rankings based on user visits. It allows administrators to
manage city statuses directly from the dashboard, improving usability
and functionality.

app/admin/ahoy_dashboard.rb

@@ -71,6 +71,25 @@ ActiveAdmin.register_page "Ahoy Dashboard" do
       end
     end
 
+    columns do
+      column do
+        panel "城市排名" do
+          table_for City.least_popular_active do
+            column("城市") { |city| link_to(city.name, admin_city_path(city)) }
+            column("访问量") { |city| city.view_count }
+            column("状态") { |city| status_tag(city.active? ? "活跃" : "停用") }
+            # column("状态") { |city| status_tag(city.active? ? "活跃" : "停用") }
+            column("操作") { |city|
+              button_to "停用",
+                        admin_ahoy_dashboard_toggle_city_status_path(city_id: city.id),
+                        method: :post,
+                        data: { confirm: "确定要停用 #{city.name} 吗？" }
+            }
+          end
+        end
+      end
+    end
+
     # 添加一个事件列表面板
     panel "最近事件" do
       table_for Ahoy::Event.order(time: :desc).limit(10) do