Fix missing H1 on list-style pages via SectionHeading template

SectionHeading always rendered its title as <h2>, so every page whose
only heading came from a shared section component (services hub,
promotions, cases, faq, contact, reviews, blog list) had no <h1> at
all. Add a level prop (default h2) and pass headingLevel="h1" from
each page where that section is the page's own top-level heading.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013otXCiTZsxdZ4SJKZ9wUky

public-site/app/otzyvy/page.jsx

@@ -15,7 +15,7 @@ export default async function ReviewsPage() {
   return (
     <div>
       <Header />
-      <Reviews reviews={reviews} />
+      <Reviews reviews={reviews} headingLevel="h1" />
       <Footer />
     </div>
   );