chore: update meta keywords for SEO

- Modify keywords in CitiesController for better
  categorization of AI art and weather art.
- Update keywords in WeatherArtsController to include
  city country name and description.
- Add keywords in application layout for overall site
  SEO improvement.

These changes aim to improve search engine visibility
and better describe the content related to AI-generated
weather art.

app/controllers/cities_controller.rb

@@ -46,7 +46,7 @@ class CitiesController < ApplicationController
     set_meta_tags(
       title: @city.name,
       description: "Experience #{@city.name}'s weather through AI-generated art. Daily updates of weather conditions visualized through artificial intelligence.",
-      keywords: "#{@city.name}, #{@city.country.name}, weather art, AI visualization",
+      keywords: "#{@city.name}, #{@city.country.name}, ai art, weather art, AI visualization",
       og: {
         image: @city.latest_weather_art&.image&.attached? ? url_for(@city.latest_weather_art.image) : nil
       }

app/controllers/weather_arts_controller.rb

@@ -17,7 +17,7 @@ class WeatherArtsController < ApplicationController
     set_meta_tags(
       title: "#{@city.name} Weather Art - #{@weather_art.weather_date.strftime('%B %d, %Y')}",
       description: "#{@city.name}'s weather visualized through AI art. #{@weather_art.description} at #{@weather_art.temperature}°C.",
-      keywords: "#{@city.name}, weather art, #{@weather_art.description}, AI visualization",
+      keywords: "#{@city.name}, #{@city.country.name}, ai art, weather art, AI visualization, #{@weather_art.description}",
       og: {
         image: @weather_art.image.attached? ? url_for(@weather_art.image) : nil
       }

app/views/layouts/application.html.erb

@@ -11,6 +11,7 @@
           og: {
             site_name: 'TodayAIWeather',
             type: 'website',
+            keywords: "ai art, weather art, AI visualization, today ai weather",
             url: request.original_url
           },
           alternate: {