Fix #5362: Suggest ai-generated as a translated tag from pixiv response

app/logical/source/extractor/pixiv.rb

@@ -104,10 +104,17 @@ module Source
       end
 
       def tags
-        api_illust.dig(:tags, :tags).to_a.map do |item|
+        tags = api_illust.dig(:tags, :tags).to_a.map do |item|
           tag = item[:tag]
           [tag, "https://www.pixiv.net/search.php?s_mode=s_tag_full&#{{word: tag}.to_param}"]
         end
+
+        if api_illust["aiType"] == 2
+          # XXX There's no way to search for posts with the AI flag on Pixiv. The "AI" tag is the closest equivalent.
+          tags += [["AI", "https://www.pixiv.net/tags/AI/artworks"]]
+        end
+
+        tags
       end
 
       def normalize_tag(tag)