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/faq/page.jsx

@@ -32,7 +32,7 @@ export default async function FaqPage() {
         <script type="application/ld+json" dangerouslySetInnerHTML={{ __html: JSON.stringify(faqSchema) }} />
       )}
       <Header />
-      <Faq faqs={faqs} />
+      <Faq faqs={faqs} headingLevel="h1" />
       <Footer />
     </div>
   );