The skills.sh source was returning ~858 unique skills from a hardcoded
list of 28 popular keyword searches (each capped at 50 results). The
real catalog is ~20k — exposed via sitemap-skills-{1,2}.xml linked from
the site's sitemap index.
Switch the empty-query path in SkillsShSource.search() to walk the
sitemap instead of scraping the homepage's curated featured strip.
Falls back to the homepage scrape if the sitemap is unreachable.
build_skills_index.crawl_skills_sh() now just calls search("", limit=0)
instead of running 28 keyword searches — same result in one HTTP round
instead of 28.
Also handle a httpx + brotlicffi interaction: the per-skill sitemaps
are ~900 KB brotli-compressed and the cffi backend's streaming decode
chokes on them. Forcing Accept-Encoding to gzip dodges the bug without
requiring a brotli library upgrade.
E2E against live skills.sh: 19,932 unique skills walked in 0.7s.
Tests: 137 pass (+1 new regression test exercising the sitemap path).
Floor for skills.sh raised 100 → 10,000 in EXPECTED_FLOORS so a future
regression hard-fails the build.