Enhance Inkbunny job processing and update post handling

- Updated Rakefile to enqueue periodic jobs for Inkbunny latest posts, improving background processing.
- Added a check in UpdatePostsJob to handle cases with empty post IDs, preventing unnecessary processing.
- Enhanced IndexedPost model to support posting dates for Inkbunny posts.
- Refined view for displaying indexed posts, improving the presentation of posting dates and user experience.

Rakefile

@@ -42,12 +42,19 @@ task periodic_tasks: %i[environment set_logger_stdout] do
       Rake::Task["fa:browse_page_job"].execute
       Rake::Task["fa:home_page_job"].execute
       Rake::Task["e621:posts_index_job"].execute
-      Domain::Inkbunny::Job::UpdatePostsJob.set(
+      puts "enqueue periodic jobs"
+      sleep 1.minute
+    end
+  end
+
+  Thread.new do
+    loop do
+      puts "enqueue inkbunny latest posts"
+      Domain::Inkbunny::Job::LatestPostsJob.set(
         queue: "inkbunny",
         priority: -20,
       ).perform_later({})
-      puts "enqueue periodic jobs"
-      sleep 1.minute
+      sleep 2.minutes
     end
   end