accept Bluesky handles without @ in login command

tootify

···
 
   if name =~ /\A[^@]+@[^@]+\z/
     app.login_to_mastodon(name)
-  elsif name =~ /\A@[^@]+\z/
+  elsif name =~ /\A@?[^@]+\z/
     app.login_to_bluesky(name)
   elsif name.nil?
     print_help