FIT-1010: add JS to track enterprise CTA using GA4 (#195)

Author: matt-bernstein

fern/docs.yml

@@ -77,3 +77,7 @@ favicon: ./images/favicon.ico
 analytics:
   ga4:
     measurement-id: G-326708547
+
+js:
+  - path: ./js/analytics-enterprise-cta.js
+    strategy: afterInteractive

fern/js/analytics-enterprise-cta.js

@@ -0,0 +1,19 @@
+document.addEventListener('DOMContentLoaded', function() {
+  const links = document.querySelectorAll('a[href^="https://humansignal.com/goenterprise"]');
+  if (links.length === 0) {
+    return;
+  }
+  links.forEach((link, index) => {
+    link.addEventListener('click', function() {
+      if (typeof gtag === 'function') {
+        gtag('event', 'enterprise_cta_click', {
+          button_index: index,
+          button_text: link.innerText || '', 
+          target_url: link.href,
+          page_path: window.location.pathname
+        });
+      }
+    });
+  });
+});
+