feat: improve weather art display and generation

- Display the latest weather art on the cities index page.
- Update the weather art preview image size to be big.
- Improve image display by using webp format.
- Adjust the daily and per-run generation limits.

These changes enhance the user experience by providing more
up-to-date and visually appealing content, while also controlling
the resource usage during image generation.

app/controllers/cities_controller.rb

@@ -5,6 +5,7 @@ class CitiesController < ApplicationController
   def index
     @regions = Region.order(:name)
     @cities = City.includes(:country, country: :region).order(:name)
+    @latest_arts = WeatherArt.includes(:city, :image_attachment).latest(1)
 
     if params[:query].present?
       @cities = @cities.search_by_name(params[:query])

app/models/weather_art.rb

@@ -120,7 +120,7 @@ class WeatherArt < ApplicationRecord
     medium: [ 896, 512 ],
     small: [ 448, 256 ]
   }.freeze
-  def preview_image(size = :medium)
+  def preview_image(size = :big)
     return nil unless image.attached?
 
     width, height = PREVIEW_DIMENSIONS[size] || PREVIEW_DIMENSIONS[:medium]

app/views/cities/index.html.erb

@@ -1,7 +1,7 @@
 <!-- app/views/cities/index.html.erb -->
 <div class="min-h-screen">
   <!-- 页面标题和背景 -->
-  <% featured_art = WeatherArt.includes(:city).joins(:image_attachment).order(created_at: :desc).first %>
+  <% featured_art = @latest_arts.first %>
   <div class="relative bg-base-100">
     <!-- 背景图像和渐变 -->
     <% if featured_art&.image&.attached? %>

app/views/home/index.html.erb

@@ -3,7 +3,7 @@
   <section class="h-screen-90 relative overflow-hidden">
     <% if @latest_arts.first&.image&.attached? %>
       <div class="absolute inset-0">
-        <%= image_tag @latest_arts.first.preview_image(:large).processed, class: "w-full h-full object-cover" %>
+        <%= image_tag @latest_arts.first.webp_image.processed, class: "w-full h-full object-cover" %>
         <div class="absolute inset-0 bg-gradient-to-r from-base-100/90 to-base-100/50"></div>
       </div>
     <% end %>

app/workers/batch_generate_weather_arts_worker.rb

@@ -4,8 +4,8 @@ class BatchGenerateWeatherArtsWorker
   GENERATION_INTERVAL = 36.hours
   MAX_DURATION = 5.minutes
   SLEEP_DURATION = 10.seconds
-  DAILY_GENERATION_LIMIT = 50  # 每日生成图片上限
-  PER_RUN_GENERATION_LIMIT = 5 # 每次运行生成图片上限
+  DAILY_GENERATION_LIMIT = 60  # 每日生成图片上限
+  PER_RUN_GENERATION_LIMIT = 3 # 每次运行生成图片上限
 
   def perform(*args)
     start_time = Time.current