rename app_router to app-router to be consistent with js module naming.
use fixed elements for navbar/footer views and test accordingly.
while we're at it, we should be checking that the router is assigned from options in the new thread view.
don't insert navbar into the page, just render it.
make root route actually redirect (navigate) to homepage in default locale.
.navbar selector is ambiguous now that we have a footer, use #navbar instead.