feat: implement Umami page speed tracking via Web Vitals

- Add WebVitalsTracker component using useReportWebVitals
- Report LCP, CLS, FID, FCP, TTFB, and INP as Umami events
- Include rating (good/needs-improvement/poor) for meaningful metrics

components/analytics/AnalyticsShell.tsx

@@ -9,6 +9,9 @@ const DynamicAnalyticsProvider = dynamic(() => import('./AnalyticsProvider'), {
 const DynamicScrollDepthTracker = dynamic(() => import('./ScrollDepthTracker'), {
   ssr: false,
 });
+const DynamicWebVitalsTracker = dynamic(() => import('./WebVitalsTracker'), {
+  ssr: false,
+});
 
 export default function AnalyticsShell() {
   const [shouldLoad, setShouldLoad] = useState(false);
@@ -34,6 +37,7 @@ export default function AnalyticsShell() {
     <Suspense fallback={null}>
       <DynamicAnalyticsProvider />
       <DynamicScrollDepthTracker />
+      <DynamicWebVitalsTracker />
     </Suspense>
   );
 }

components/analytics/WebVitalsTracker.tsx

@@ -0,0 +1,54 @@
+'use client';
+
+import { useReportWebVitals } from 'next/web-vitals';
+import { useAnalytics } from './useAnalytics';
+
+/**
+ * WebVitalsTracker component.
+ *
+ * Captures Next.js Web Vitals and reports them to Umami as custom events.
+ * This provides "meaningful" page speed tracking by measuring real user
+ * experiences (LCP, CLS, INP, etc.).
+ */
+export default function WebVitalsTracker() {
+  const { trackEvent } = useAnalytics();
+
+  useReportWebVitals((metric) => {
+    const { name, value, id, label } = metric;
+
+    // Determine rating (simplified version of web-vitals standards)
+    let rating: 'good' | 'needs-improvement' | 'poor' = 'good';
+
+    if (name === 'LCP') {
+      if (value > 4000) rating = 'poor';
+      else if (value > 2500) rating = 'needs-improvement';
+    } else if (name === 'CLS') {
+      if (value > 0.25) rating = 'poor';
+      else if (value > 0.1) rating = 'needs-improvement';
+    } else if (name === 'FID') {
+      if (value > 300) rating = 'poor';
+      else if (value > 100) rating = 'needs-improvement';
+    } else if (name === 'FCP') {
+      if (value > 3000) rating = 'poor';
+      else if (value > 1800) rating = 'needs-improvement';
+    } else if (name === 'TTFB') {
+      if (value > 1500) rating = 'poor';
+      else if (value > 800) rating = 'needs-improvement';
+    } else if (name === 'INP') {
+      if (value > 500) rating = 'poor';
+      else if (value > 200) rating = 'needs-improvement';
+    }
+
+    // Report to Umami
+    trackEvent('web-vital', {
+      metric: name,
+      value: Math.round(name === 'CLS' ? value * 1000 : value), // CLS is a score, multiply by 1000 to keep as integer if preferred
+      rating,
+      id,
+      label,
+      path: typeof window !== 'undefined' ? window.location.pathname : undefined,
+    });
+  });
+
+  return null;
+}