`ci.yml` runs what `make check` runs, in three jobs: format, clippy and the
tests, after building the frontend, because the binary embeds web/dist and does
not compile without it; svelte-check; and the wiki check, so a change to a
command's help that forgets `make wiki` fails before it lands.
`wiki.yml` publishes docs/wiki to the repository's GitHub wiki on every push to
main that touches the pages or a file the generated ones are read from. It
generates the pages afresh rather than trusting the committed ones, lays them
out with `--publish` in a clone of the wiki, and pushes only when something
changed. GitHub makes a wiki's repository only once its first page exists, so
one page has to be saved by hand before the first run; the comment at the top
says so.
