fix(a11y): remove nested <main> landmarks under (home) layout

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

surfsense_web/app/(home)/free/page.tsx

@@ -156,7 +156,7 @@ export default async function FreeHubPage() {
 	const seoModels = models.filter((m) => m.seo_slug);
 
 	return (
-		<main className="min-h-screen pt-20">
+		<div className="min-h-screen pt-20">
 			<JsonLd
 				data={{
 					"@context": "https://schema.org",
@@ -382,6 +382,6 @@ export default async function FreeHubPage() {
 					</ul>
 				</nav>
 			</article>
-		</main>
+		</div>
 	);
 }