feat: Page Editor v1.0 - canonical schema, SSR parity, and migration

Major improvements to WooNooW Page Editor system:

Schema & Architecture:
- Canonical section schema with unified sectionSchema.ts
- Normalized feature-grid to use items (not features)
- Standardized default values across all section types
- Schema versioning with automatic migration on read

Backend (PHP):
- Enhanced PlaceholderRenderer with typed output contracts
- Added fallback behavior for empty/invalid dynamic sources
- Added caching support for post data resolution
- New SchemaMigration class for backward compatibility
- New Features class for feature flags
- Enhanced PageSSR with full style support
- Removed controller-level special-casing for related_posts

Frontend (Admin SPA):
- Updated CanvasRenderer with schema-aware transformation
- Enhanced InspectorPanel with canonical schema metadata
- Added new section renderers

Frontend (Customer SPA):
- New section components: BentoCategoryGrid, MarqueeBanner, ProductCarousel, ShoppableImage
- Updated FeatureGridSection for items prop contract

Testing:
- Add PHP tests: SchemaMigrationTest, PlaceholderRendererTest, PageSSRTest
- Add TypeScript tests: schema-integration, feature-grid-regression
- Add parity tests for React vs SSR content matching
- Add CI script: check-schema-drift.mjs
- Add VERIFICATION_CHECKLIST.md

Documentation:
- RELEASE_NOTES-v1.0.md with full release notes
- docs/PAGE_EDITOR_SECTION_SCHEMA_V1.md
- docs/PAGE_EDITOR_SSR_COVERAGE_AUDIT.md

customer-spa/src/layouts/LayoutWrapper.tsx

@@ -3,6 +3,7 @@ import { useLocation } from 'react-router-dom';
 import { useCheckoutSettings, useThankYouSettings } from '../hooks/useAppearanceSettings';
 import { MinimalHeader } from '../components/Layout/MinimalHeader';
 import { MinimalFooter } from '../components/Layout/MinimalFooter';
+import { useTheme } from '../contexts/ThemeContext';
 
 interface LayoutWrapperProps {
   children: ReactNode;
@@ -14,6 +15,7 @@ export function LayoutWrapper({ children, header, footer }: LayoutWrapperProps)
   const location = useLocation();
   const checkoutSettings = useCheckoutSettings();
   const thankYouSettings = useThankYouSettings();
+  const { colorMode } = useTheme();
 
   // Determine visibility settings based on current route
   let headerVisibility = 'show';
@@ -45,7 +47,10 @@ export function LayoutWrapper({ children, header, footer }: LayoutWrapperProps)
   };
 
   return (
-    <div className="layout-wrapper min-h-screen flex flex-col" style={backgroundColor ? { backgroundColor } : undefined}>
+    <div
+      className="layout-wrapper min-h-screen flex flex-col"
+      style={backgroundColor && colorMode !== 'dark' ? { backgroundColor } : undefined}
+    >
       {renderHeader()}
       <main className="flex-1">
         {children}