Bug: static page links to dynamic page by default

Emails can be listed statically, for example:

https://lists.apache.org/api/static.lua/users@ponymail.apache.org

This provides a link to the full e-mail, e.g.

https://lists.apache.org/thread.html/%3C574D1CD9.2070901@apache.org%3E

However this is for the dynamic version of the page; the default link should be to the static page.

Start at the static.lua endpoint and trace how it constructs the link to thread.html for the full email. Change the default link target to the static page, then verify that statically listed emails no longer link to the dynamic page.

Written by the indexing model from the issue text.