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.

backend/igny8_core/business/site_building/services/page_generation_service.py

@@ -23,10 +23,14 @@ class PageGenerationService:
 
     def __init__(self):
         self.content_service = ContentGenerationService()
+        # Site Builder uses its own AI function for structured block generation
+        from igny8_core.ai.functions.generate_page_content import GeneratePageContentFunction
+        self.page_content_function = GeneratePageContentFunction()
 
     def generate_page_content(self, page_blueprint: PageBlueprint, force_regenerate: bool = False) -> dict:
         """
         Generate (or regenerate) content for a single Site Builder page.
+        Uses Site Builder specific AI function that outputs structured JSON blocks.
 
         Args:
             page_blueprint: Target PageBlueprint instance.
@@ -35,19 +39,39 @@ class PageGenerationService:
         if not page_blueprint:
             raise ValueError("Page blueprint is required")
 
-        task = self._ensure_task(page_blueprint, force_regenerate=force_regenerate)
-
-        # Mark page as generating before handing off to Writer pipeline
+        # Mark page as generating
         page_blueprint.status = 'generating'
         page_blueprint.save(update_fields=['status', 'updated_at'])
 
         account = page_blueprint.account
+        
+        # Use Site Builder specific AI function for structured block generation
+        from igny8_core.ai.engine import AIEngine
+        
+        ai_engine = AIEngine(account=account)
+        
         logger.info(
-            "[PageGenerationService] Triggering content generation for page %s (task %s)",
+            "[PageGenerationService] Generating structured content for page %s using generate_page_content function",
             page_blueprint.id,
-            task.id,
         )
-        return self.content_service.generate_content([task.id], account)
+        
+        # Execute Site Builder page content generation
+        result = ai_engine.execute(
+            self.page_content_function,
+            {'ids': [page_blueprint.id]}
+        )
+        
+        if result.get('error'):
+            page_blueprint.status = 'draft'
+            page_blueprint.save(update_fields=['status', 'updated_at'])
+            raise ValueError(f"Content generation failed: {result.get('error')}")
+        
+        return {
+            'success': True,
+            'page_id': page_blueprint.id,
+            'blocks_count': result.get('blocks_count', 0),
+            'content_id': result.get('content_id')
+        }
 
     def regenerate_page(self, page_blueprint: PageBlueprint) -> dict:
         """Force regeneration by dropping the cached task metadata."""