feat: enhance contact page with newsletter and social cards

Add newsletter_card component with :card and :inline variants to share
between footer and contact page. Add social_links_card component with
full-width icon+text cards for better discoverability.

Improve contact_form with optional email link and response time display,
keeping important contact info above the fold. Reorganize contact page
layout with form on left, info cards on right.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

lib/simpleshop_theme_web/components/page_templates/contact.html.heex

@@ -15,7 +15,7 @@
     />
 
     <div class="grid gap-8 md:grid-cols-2 mb-12">
-      <.contact_form />
+      <.contact_form email="hello@example.com" response_time="We typically respond within 24 hours" />
 
       <div class="space-y-6">
         <.order_tracking_card />
@@ -26,9 +26,9 @@
           %{label: "Returns", value: "Happy to help with faulty or damaged items"}
         ]} />
 
-        <.contact_info_card email="hello@example.com" />
+        <.newsletter_card />
 
-        <.social_links />
+        <.social_links_card />
       </div>
     </div>
   </main>