Jobs fixes

This adds a new Interactive Developer job and removes the JS Engineer role, but also fixes a few bugs, namely the devblog vanishing due to CAPI v2 switch, and system JS being updated (at least, when I ran it locally) and all the file references failing.
If this title was inside `nav`, it would produce a better document outline. It might also be better for screen readers, although I don't know much about those.

Just an idea :smile: