Add aksrt_get_null / widget null helpers with null.svg, use them in
sidebar widgets, comments empty, and related posts; when PM is off show
post rewards entry on the single author bar.
Add REST comment/list + comment/submit HTML fragments, shared query
renderer for order/author/hottest, fix load-more policy and DOM
targets, and stop full-page scrapes for order/author/reload.
Apply comments_template_query_args for newest/hottest/author-only,
keep filter bar visible under empty author filters, and restyle order
tabs/buttons with Zibll-compatible classes.
kate522