fix(locale): align all English MDX page links and add automated links validation test to prevent language drift

content/en/kompetenzen.mdx

@@ -11,7 +11,7 @@ layout: "fullBleed"
   description="As a full-service partner in the field of cable civil engineering, we cover the entire spectrum of modern infrastructure projects."
   videoUrl="/assets/videos/web/hero-bohrung.mp4"
   linkText="Get in Touch"
-  linkHref="/en/kontakt"
+  linkHref="/en/contact"
   secondaryCtaLabel="View References"
   secondaryCtaHref="/en/#referenzen"
 />
@@ -20,7 +20,7 @@ layout: "fullBleed"
   badge="Core Competencies"
   title="Precision & Performance"
   ctaLabel="Request a project"
-  ctaHref="/en/kontakt"
+  ctaHref="/en/contact"
   items={[
     {
       title: "Cable Construction",