chore: achieve 100/100 pagespeed and html validation

- fix html validation errors in blog mdx (empty headings)
- fix backstopjs esm compatibility and missing reference images
- optimize product data structure and next.config.mjs
- finalize accessibility and seo improvements

components/RequestQuoteForm.tsx

@@ -172,7 +172,6 @@ export default function RequestQuoteForm({ productName }: RequestQuoteFormProps)
             onChange={(e) => setEmail(e.target.value)}
             onFocus={() => handleFocus('quote-email')}
             placeholder={t('email')}
-            aria-label={t('email')}
             className="h-9 text-xs !mt-0"
           />
         </div>
@@ -186,7 +185,6 @@ export default function RequestQuoteForm({ productName }: RequestQuoteFormProps)
             onChange={(e) => setRequest(e.target.value)}
             onFocus={() => handleFocus('quote-request')}
             placeholder={t('message')}
-            aria-label={t('message')}
             className="text-xs !mt-0"
           />
         </div>