Add generate_page_content functionality for structured page content generation

- Introduced a new AI function `generate_page_content` to create structured content for website pages using JSON blocks.
- Updated `AIEngine` to handle the new function and return appropriate messages for content generation.
- Enhanced `PageGenerationService` to utilize the new AI function for generating page content based on blueprints.
- Modified `prompts.py` to include detailed content generation requirements for the new function.
- Updated site rendering logic to accommodate structured content blocks in various layouts.

sites/src/pages/SiteRenderer.tsx

@@ -41,36 +41,32 @@ function SiteRenderer() {
   }
 
   // Build navigation from site definition
-  // Show pages that are published, ready, or in navigation (excluding home and draft/generating)
-  const navigation = siteDefinition.navigation || siteDefinition.pages
-    .filter(p => 
-      p.slug !== 'home' && 
-      (p.status === 'published' || p.status === 'ready' || siteDefinition.navigation?.some(n => n.slug === p.slug))
-    )
-    .sort((a, b) => {
-      // Try to get order from navigation or use page order
-      const navA = siteDefinition.navigation?.find(n => n.slug === a.slug);
-      const navB = siteDefinition.navigation?.find(n => n.slug === b.slug);
-      return (navA?.order ?? a.order ?? 0) - (navB?.order ?? b.order ?? 0);
-    })
-    .map(page => ({
-      label: page.title,
-      slug: page.slug,
-      order: page.order || 0
-    }));
+  // Show all published/ready pages (excluding home and draft/generating)
+  // Use explicit navigation if available, otherwise auto-generate from pages
+  const navigation = siteDefinition.navigation && siteDefinition.navigation.length > 0
+    ? siteDefinition.navigation
+    : siteDefinition.pages
+        .filter(p => 
+          p.slug !== 'home' && 
+          (p.status === 'published' || p.status === 'ready') &&
+          p.status !== 'draft' && 
+          p.status !== 'generating'
+        )
+        .sort((a, b) => (a.order || 0) - (b.order || 0))
+        .map(page => ({
+          label: page.title,
+          slug: page.slug,
+          order: page.order || 0
+        }));
 
   // Filter pages based on current route
   const currentPageSlug = pageSlug || 'home';
   const currentPage = siteDefinition.pages.find(p => p.slug === currentPageSlug);
   
-  // If specific page requested, show only that page; otherwise show all published/ready pages
-  const pagesToRender = currentPageSlug && currentPageSlug !== 'home' && currentPage
+  // Show only the current page (home page on home route, specific page on page route)
+  const pagesToRender = currentPage
     ? [currentPage]
-    : siteDefinition.pages.filter(p => 
-        p.status === 'published' || 
-        p.status === 'ready' || 
-        (p.slug === 'home' && p.status !== 'draft' && p.status !== 'generating')
-      );
+    : []; // Fallback: no page found
 
   return (
     <div className="site-renderer" style={{