The site's pre-rendered public/**/index.html pages each embed their own copy
of the Services mega-dropdown and do not read src/partials/nav.html, so the
earlier nav.html-only edit never appeared. inject_healthcare_nav.py adds the
canonical Healthcare block (Medicare Revalidation, Medicare Enrollment, NPI/
NPPES Services, free NPI Compliance Check) to the desktop Column 3 + mobile
menu of all 80 static pages. Idempotent.
