fix: switch to PostHogProvider per official React integration guide (#112)

- Install @posthog/react and wrap app with PostHogProvider
- Use VITE_PUBLIC_POSTHOG_KEY and VITE_PUBLIC_POSTHOG_HOST env vars
- Use defaults: '2026-01-30' for recommended settings
- Remove manual initAnalytics() call — Provider handles initialization
- Analytics module now checks posthog.__loaded for readiness

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

frontend/src/lib/analytics.ts

@@ -2,29 +2,24 @@
  * PostHog product analytics wrapper.
  *
  * Tracks key user actions to understand product usage, activation,
- * and engagement. All events are lightweight discrete actions — no
- * pageviews or mouse tracking.
+ * and engagement. All events are lightweight discrete actions.
  *
  * Free tier: 1M events/month (more than enough for current scale).
+ *
+ * PostHog is initialized via PostHogProvider in main.tsx.
+ * This module provides typed event helpers that import posthog-js directly
+ * (valid per PostHog docs for non-component code).
  */
 import posthog from 'posthog-js'
 
-const POSTHOG_KEY = import.meta.env.VITE_POSTHOG_KEY as string | undefined
-const POSTHOG_HOST = (import.meta.env.VITE_POSTHOG_HOST as string) || 'https://us.i.posthog.com'
-
-let initialized = false
-
-/** Initialize PostHog. Call once on app startup. */
-export function initAnalytics() {
-  if (initialized || !POSTHOG_KEY) return
-  posthog.init(POSTHOG_KEY, {
-    api_host: POSTHOG_HOST,
-    autocapture: false,       // We track events explicitly — no auto-capture
-    capture_pageview: false,  // SPA — we'll track meaningful navigations, not every route
-    capture_pageleave: false,
-    persistence: 'localStorage',
-  })
-  initialized = true
+/** Check if PostHog has been initialized (by the Provider). */
+function isReady(): boolean {
+  try {
+    // posthog-js sets __loaded when init completes
+    return !!(posthog as unknown as { __loaded?: boolean }).__loaded
+  } catch {
+    return false
+  }
 }
 
 /** Identify a logged-in user. Call after login/fetchUser. */
@@ -35,7 +30,7 @@ export function identifyUser(user: {
   is_super_admin?: boolean
   account_id?: string
 }) {
-  if (!initialized) return
+  if (!isReady()) return
   posthog.identify(user.id, {
     email: user.email,
     role: user.role,
@@ -48,7 +43,7 @@ export function identifyUser(user: {
 
 /** Reset identity on logout. */
 export function resetAnalytics() {
-  if (!initialized) return
+  if (!isReady()) return
   posthog.reset()
 }
 
@@ -56,7 +51,7 @@ export function resetAnalytics() {
 
 /** Track a named event with optional properties. */
 function track(event: string, properties?: Record<string, unknown>) {
-  if (!initialized) return
+  if (!isReady()) return
   posthog.capture(event, properties)
 }