fix(hosting): propagate preview token in nav links + enrich pages with scraped content

Preview token propagation:
- JavaScript in storefront base.html appends _preview query param to
  all internal links when in preview mode, so clicking nav items
  (Services, Contact, etc.) preserves the preview bypass

Scraped content enrichment:
- POC builder now appends first 5 scraped paragraphs to about/services/
  projects pages, so the POC shows actual content from the prospect's
  site instead of just generic template text
- Extracts tagline from second scraped heading

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

app/templates/storefront/base.html

@@ -220,6 +220,22 @@
         <a href="https://hostwizard.lu" style="color:white;text-decoration:none;padding:6px 16px;border:1px solid rgba(255,255,255,0.4);border-radius:6px;font-size:13px;" target="_blank">hostwizard.lu</a>
     </div>
     <style>header { margin-top: 48px !important; }</style>
+    <script>
+    // Propagate preview token to all internal links
+    document.addEventListener('DOMContentLoaded', function() {
+        var params = new URLSearchParams(window.location.search);
+        var token = params.get('_preview');
+        if (!token) return;
+        document.querySelectorAll('a[href]').forEach(function(a) {
+            var href = a.getAttribute('href');
+            if (href && (href.startsWith('/') || href.startsWith(window.location.origin)) && !href.startsWith('//')) {
+                var url = new URL(href, window.location.origin);
+                url.searchParams.set('_preview', token);
+                a.setAttribute('href', url.pathname + url.search);
+            }
+        });
+    });
+    </script>
     {% endif %}
 
     {# Mobile menu panel #}