Change hashtags to preserve first-used casing (#11416)

app/services/hashtag_query_service.rb

@@ -14,7 +14,7 @@ class HashtagQueryService < BaseService
 
   private
 
-  def tags_for(tags)
-    Tag.where(name: tags.map(&:downcase)) if tags.presence
+  def tags_for(names)
+    Tag.matching_name(names) if names.presence
   end
 end

app/services/process_hashtags_service.rb

@@ -5,9 +5,7 @@ class ProcessHashtagsService < BaseService
     tags    = Extractor.extract_hashtags(status.text) if status.local?
     records = []
 
-    tags.map { |str| str.mb_chars.downcase }.uniq(&:to_s).each do |name|
-      tag = Tag.where(name: name).first_or_create(name: name)
-
+    Tag.find_or_create_by_names(tags) do |tag|
       status.tags << tag
       records << tag