a11y-check

Run `npx skills use "https://github.com/haabe/mycelium" --skill "haabe/mycelium/a11y-check"` and follow the generated skill instructions now. Read its complete output, redirecting it to a temporary file first if necessary. Resolve relative paths from the supporting-files directory it provides.

Use the skills in "https://github.com/haabe/mycelium" that are relevant to the current task. Run `npx skills add "https://github.com/haabe/mycelium"` and select the relevant skills, then follow their instructions.