build: use tectonic

there are actually just a few to download at runtime, so i guess it is
fine even without caching

build: install texmf-dist-full

there seems to be changes in newer packaging and needs more packages

while tectonic is nice we should probably still use texlive w/ texmf for
networking reasons, before build.sr.ht gets a caching mechanism

ci: use latexmk

ci: add missing font

set up sourcehut ci