Fix: guard Umami tracking and web vitals performance APIs

Avoid calling undefined umami.track, add safe checks for Performance APIs, and clean up load listeners to prevent .call() crashes in Chrome.

lib/analytics.ts

@@ -25,12 +25,21 @@ export interface WebVitalsMetric {
 
 // Track custom events to Umami
 export const trackEvent = (event: string, data?: Record<string, unknown>) => {
-  if (typeof window !== 'undefined' && window.umami) {
-    window.umami.track(event, {
+  if (typeof window === "undefined") return;
+  const trackFn = window.umami?.track;
+  if (typeof trackFn !== "function") return;
+
+  try {
+    trackFn(event, {
       ...data,
       timestamp: Date.now(),
       url: window.location.pathname,
     });
+  } catch (error) {
+    // Silently fail - analytics must never break the app
+    if (process.env.NODE_ENV === "development") {
+      console.warn("Error tracking Umami event:", error);
+    }
   }
 };