rubocop: fix various Rubocop warnings.

app/controllers/recommended_posts_controller.rb

@@ -4,7 +4,7 @@ class RecommendedPostsController < ApplicationController
   def index
     limit = params.fetch(:limit, 100).to_i.clamp(0, 200)
     @recs = RecommenderService.search(search_params).take(limit)
-    @posts = @recs.map { |rec| rec[:post] }
+    @posts = @recs.pluck(:post)
 
     respond_with(@recs)
   end