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'

app/[locale]/blog/[slug]/page.tsx

@@ -30,11 +30,11 @@ export async function generateMetadata({ params }: BlogPostProps): Promise<Metad
     title: post.frontmatter.title,
     description: description,
     alternates: {
-      canonical: `/${locale}/blog/${slug}`,
+      canonical: `${SITE_URL}/${locale}/blog/${slug}`,
       languages: {
-        de: `/de/blog/${slug}`,
-        en: `/en/blog/${slug}`,
-        'x-default': `/en/blog/${slug}`,
+        de: `${SITE_URL}/de/blog/${slug}`,
+        en: `${SITE_URL}/en/blog/${slug}`,
+        'x-default': `${SITE_URL}/en/blog/${slug}`,
       },
     },
     openGraph: {