The (home)/layout.tsx already wraps children in <main>. Having another
<main> inside each child page produces nested landmarks, which is
invalid HTML and confuses screen readers.
Changed the outermost wrapper from <main> → <div> in:
- surfsense_web/app/(home)/page.tsx (homepage)
- surfsense_web/app/(home)/free/page.tsx (free AI chat landing)
Other (home) descendants (login/register/privacy/terms/changelog/
announcements/blog/contact/free/[model_slug]) were already using <div>.
Closes#1191
