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

includes/Api/ProductsController.php

@@ -527,9 +527,11 @@ class ProductsController
 
 		// Virtual and downloadable
 		if (array_key_exists('virtual', $data)) {
+			error_log("Setting virtual to: " . ($data['virtual'] ? 'true' : 'false') . " for product ID: " . $product->get_id());
 			$product->set_virtual((bool) $data['virtual']);
 		}
 		if (array_key_exists('downloadable', $data)) {
+			error_log("Setting downloadable to: " . ($data['downloadable'] ? 'true' : 'false') . " for product ID: " . $product->get_id());
 			$product->set_downloadable((bool) $data['downloadable']);
 		}
 		if (array_key_exists('featured', $data)) {
@@ -887,6 +889,62 @@ class ProductsController
 		}
 		$data['gallery'] = $gallery;
 
+		// Video / rich media - stored in product meta
+		$video_url = get_post_meta($product->get_id(), '_woonoow_video_url', true) ?: '';
+		$data['video_url'] = $video_url;
+
+		// Detect embed type (youtube / vimeo / direct mp4)
+		$data['video_type'] = '';
+		if ($video_url) {
+			if (strpos($video_url, 'youtube.com') !== false || strpos($video_url, 'youtu.be') !== false) {
+				$data['video_type'] = 'youtube';
+			} elseif (strpos($video_url, 'vimeo.com') !== false) {
+				$data['video_type'] = 'vimeo';
+			} else {
+				$data['video_type'] = 'mp4';
+			}
+		}
+
+		// Media attachments - allow plugins/themes to inject additional media (e.g. 3D models, extra videos)
+		$media_attachments = apply_filters('woonoow_product_media_attachments', [], $product->get_id(), $product);
+		$data['media_attachments'] = is_array($media_attachments) ? $media_attachments : [];
+
+		// Cross-sells (shown in mini-cart / cart page)
+		$cross_sell_ids = $product->get_cross_sell_ids();
+		$cross_sells = [];
+		foreach (array_slice($cross_sell_ids, 0, 4) as $cs_id) {
+			$cs = wc_get_product($cs_id);
+			if (!$cs || !$cs->is_visible()) continue;
+			$cs_image_id = $cs->get_image_id();
+			$cross_sells[] = [
+				'id'    => $cs->get_id(),
+				'name'  => $cs->get_name(),
+				'slug'  => $cs->get_slug(),
+				'price' => $cs->get_price(),
+				'regular_price' => $cs->get_regular_price(),
+				'image' => $cs_image_id ? wp_get_attachment_url($cs_image_id) : '',
+			];
+		}
+		$data['cross_sells'] = $cross_sells;
+
+		// Upsells (shown on product page below main content)
+		$upsell_ids = $product->get_upsell_ids();
+		$upsells = [];
+		foreach (array_slice($upsell_ids, 0, 4) as $up_id) {
+			$up = wc_get_product($up_id);
+			if (!$up || !$up->is_visible()) continue;
+			$up_image_id = $up->get_image_id();
+			$upsells[] = [
+				'id'    => $up->get_id(),
+				'name'  => $up->get_name(),
+				'slug'  => $up->get_slug(),
+				'price' => $up->get_price(),
+				'regular_price' => $up->get_regular_price(),
+				'image' => $up_image_id ? wp_get_attachment_url($up_image_id) : '',
+			];
+		}
+		$data['upsells'] = $upsells;
+
 		// Variable product specifics
 		if ($product->is_type('variable')) {
 			$data['attributes'] = self::get_product_attributes($product);
@@ -993,6 +1051,8 @@ class ProductsController
 					'stock_status' => $variation->get_stock_status(),
 					'stock_quantity' => $variation->get_stock_quantity(),
 					'manage_stock' => $variation->get_manage_stock(),
+					'virtual' => $variation->is_virtual(),
+					'downloadable' => $variation->is_downloadable(),
 					'attributes' => $formatted_attributes,
 					'image_id' => $variation->get_image_id(),
 					'image_url' => $image_url,
@@ -1118,9 +1178,11 @@ class ProductsController
 				$variation->set_image_id($var_data['image_id']);
 			}
 
-			// Inherit virtual status from parent if parent is virtual
-			if ($product->is_virtual()) {
-				$variation->set_virtual(true);
+			if (array_key_exists('virtual', $var_data)) {
+				$variation->set_virtual((bool) $var_data['virtual']);
+			}
+			if (array_key_exists('downloadable', $var_data)) {
+				$variation->set_downloadable((bool) $var_data['downloadable']);
 			}
 
 			// Save variation first