Add a wiki/ folder with a .publish marker for the shared Publish wiki
workflow, a Quality workflow (shellcheck and shfmt through the shared
reusable workflow) and a manual Release workflow that builds the release
page from CHANGELOG.md.
Set switch_case_indent for *.sh in .editorconfig so shfmt accepts the
existing case layout.
Call the reusable quality-check workflow of TirSystem/github-action for the
shell files: shellcheck and shfmt -d. Add switch_case_indent to the
[*.sh] section of .editorconfig so that shfmt, which reads it, agrees with
the style the project already uses (shfmt -i 2 -ci in tests/run-tests.sh).