Lofter: simplify tag extraction logic

Now that we have a separate parsing class we can just use it to properly
parse tag urls as well.

app/logical/source/url/lofter.rb

@@ -28,7 +28,7 @@
 class Source::URL::Lofter < Source::URL
   RESERVED_SUBDOMAINS = %w[www.lofter.com i.lofter.com]
 
-  attr_reader :username, :work_id
+  attr_reader :username, :work_id, :unescaped_tag
 
   def self.match?(url)
     url.domain.in?(%w[lofter.com 127.net lf127.net])
@@ -48,6 +48,10 @@ class Source::URL::Lofter < Source::URL
       @username = $1
       @work_id = work_id
 
+    # https://gengar563.lofter.com/tag/%E5%BA%9F%E5%BC%83%E7%9B%90%E9%85%B8%E5%A4%84%E7%90%86%E5%8E%82
+    in /^([a-z0-9-]+)\.lofter\.com$/, "tag", tag
+      @unescaped_tag = CGI.unescape(tag)
+
     # http://gengar563.lofter.com
     in /^([a-z0-9-]+)\.lofter\.com$/, *rest unless host.in?(RESERVED_SUBDOMAINS)
       @username = $1