feat: add GA4 custom event tracking for configurator and voice agent

Events tracked:
- configurator_step_completed (with step number)
- configurator_brief_generated (with services and AI flag)
- voice_agent_started
- voice_agent_brief_generated

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/components/configurator/WizardContainer.tsx

@@ -3,6 +3,7 @@
 import { useState } from 'react';
 import { useLocale, useTranslations } from 'next-intl';
 import { AnimatePresence, motion } from 'framer-motion';
+import { trackEvent } from '@/lib/analytics';
 import StepServices from './StepServices';
 import StepDetails from './StepDetails';
 import StepContact from './StepContact';
@@ -90,7 +91,11 @@ export default function WizardContainer() {
 
   const goNext = () => {
     setDirection(1);
-    setCurrentStep((prev) => Math.min(prev + 1, 4) as 1 | 2 | 3 | 4);
+    setCurrentStep((prev) => {
+      const next = Math.min(prev + 1, 4) as 1 | 2 | 3 | 4;
+      trackEvent('configurator_step_completed', { step: prev });
+      return next;
+    });
   };
 
   const goBack = () => {
@@ -131,6 +136,10 @@ export default function WizardContainer() {
       setDirection(1);
       setIsGenerating(false);
       setCurrentStep(4);
+      trackEvent('configurator_brief_generated', {
+        services: formData.services.join(','),
+        ai_enabled: formData.aiEnabled,
+      });
     } catch {
       setSubmitError(t('errors.network'));
       setIsGenerating(false);

src/components/sections/Discovery.tsx

@@ -5,6 +5,7 @@ import { useLocale, useTranslations } from 'next-intl';
 import { motion, AnimatePresence } from 'framer-motion';
 import { MessageCircle } from 'lucide-react';
 import { revealVariants, staggerContainer, viewportOnce } from '@/lib/animations';
+import { trackEvent } from '@/lib/analytics';
 import VoiceAgentProvider from '@/components/configurator/VoiceAgentProvider';
 import VoiceAgent from '@/components/configurator/VoiceAgent';
 import StepComplete from '@/components/configurator/StepComplete';
@@ -36,6 +37,7 @@ export default function Discovery() {
 
   const handleOpen = () => {
     setIsOpen(true);
+    trackEvent('voice_agent_started');
     // Scroll to panel after it renders
     requestAnimationFrame(() => {
       panelRef.current?.scrollIntoView({ behavior: 'smooth', block: 'start' });
@@ -44,6 +46,7 @@ export default function Discovery() {
 
   const handleComplete = (brief: string, formData: WizardFormData) => {
     setCompleted({ brief, formData });
+    trackEvent('voice_agent_brief_generated');
   };
 
   const handleReset = () => {

src/lib/analytics.ts

@@ -0,0 +1,12 @@
+/**
+ * Send a custom event to Google Analytics 4.
+ * Safe to call anywhere — silently no-ops if gtag isn't loaded.
+ */
+export function trackEvent(
+  eventName: string,
+  params?: Record<string, string | number | boolean>,
+) {
+  if (typeof window !== 'undefined' && typeof window.gtag === 'function') {
+    window.gtag('event', eventName, params)
+  }
+}

src/types/global.d.ts

@@ -0,0 +1,3 @@
+interface Window {
+  gtag?: (...args: unknown[]) => void
+}