feat(cms): CMS-driven homepages, products section, placeholder resolution

- Add ProductCard/ProductsSection schema and _products.html section macro
- Rewrite seed script with 3-platform homepage sections (wizard, OMS, loyalty),
  platform marketing pages, and store defaults with {{store_name}} placeholders
- Add resolve_placeholders() to ContentPageService for store default pages
- Fix SQLAlchemy filter bugs: replace Python `is None` with `.is_(None)` across
  all ContentPageService query methods (was silently breaking all platform page lookups)
- Remove hardcoded orion fallback and delete homepage-orion.html
- Add placeholder hint box with click-to-copy in admin content page editor
- Export ProductCard/ProductsSection from cms schemas __init__

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/modules/cms/routes/pages/storefront.py

@@ -101,9 +101,17 @@ async def generic_content_page(
         },
     )
 
+    # Resolve placeholders in store default pages ({{store_name}}, etc.)
+    page_content = page.content
+    if page.is_store_default and store:
+        page_content = content_page_service.resolve_placeholders(page.content, store)
+
+    context = get_storefront_context(request, db=db, page=page)
+    context["page_content"] = page_content
+
     return templates.TemplateResponse(
         "cms/storefront/content-page.html",
-        get_storefront_context(request, db=db, page=page),
+        context,
     )