feat(analytics): implement total transparency suite and SEO metadata standardization

- Added global ScrollDepthTracker (25%, 50%, 75%, 100%)
- Implemented ProductEngagementTracker for deep product analytics
- Added field-level tracking to ContactForm and RequestQuoteForm
- Standardized SEO metadata (canonical, alternates, x-default) across all routes
- Created reusable TrackedLink and TrackedButton components for server components
- Fixed 'useAnalytics' hook error in Footer.tsx by adding 'use client'

components/analytics/ProductEngagementTracker.tsx

@@ -0,0 +1,50 @@
+'use client';
+
+import { useEffect } from 'react';
+import { useAnalytics } from './useAnalytics';
+import { AnalyticsEvents } from './analytics-events';
+
+interface ProductEngagementTrackerProps {
+  productName: string;
+  productSlug: string;
+  categories: string[];
+  sku?: string;
+}
+
+/**
+ * ProductEngagementTracker
+ * Deep analytics for product pages.
+ * Tracks specific view events with full metadata for sales analysis.
+ */
+export default function ProductEngagementTracker({
+  productName,
+  productSlug,
+  categories,
+  sku,
+}: ProductEngagementTrackerProps) {
+  const { trackEvent } = useAnalytics();
+
+  useEffect(() => {
+    // Standardized product view event for "High-Fidelity" sales insights
+    trackEvent(AnalyticsEvents.PRODUCT_VIEW, {
+      product_id: productSlug,
+      product_name: productName,
+      product_sku: sku,
+      product_categories: categories.join(', '),
+      location: 'pdp_standard',
+    });
+
+    // We can also track "Engagement Start" to measure dwell time later
+    const startTime = Date.now();
+
+    return () => {
+      const dwellTime = Math.round((Date.now() - startTime) / 1000);
+      trackEvent('pdp_dwell_time', {
+        product_id: productSlug,
+        seconds: dwellTime,
+      });
+    };
+  }, [productName, productSlug, categories, sku, trackEvent]);
+
+  return null;
+}