Previously the pages Remark42 serves from /web/ carried a build-time host.
The `{% REMARK_URL %}` placeholder is substituted during the image and
release-asset builds, both of which write `http://127.0.0.1:8080`. Docker
rewrites it again at container start from REMARK_URL, but a release binary
has no equivalent step, so it serves demo, counter, last-comments and
deleteme pages pointing at the visitor's own loopback address. `counter.ejs`
additionally had that address hardcoded in two "note" links, which no
substitution touched.
These pages are served by Remark42 itself, so the host is whatever origin and
path prefix delivered them. Deriving it from `location` is correct at the root
and under a path prefix alike, and needs no build-time value. Sibling links
are now relative for the same reason.
`site_id` is left as a literal so the startup substitution in docker-init.sh
keeps matching it.
Reported by @andreas-hempel.
Resolves#1996.
Dmitry VerkhoturovandUmputun
8801903d01