feat: PostHog 集成\

1. ✅ 安装依赖: posthog-js@^1.280.1
  2. ✅ 创建核心文件:
    - src/lib/posthog.js - PostHog SDK 封装（271 行）
    - src/lib/constants.js - 事件常量定义（AARRR 框架）
    - src/hooks/usePostHog.js - PostHog React Hook
    - src/hooks/usePageTracking.js - 页面追踪 Hook
    - src/components/PostHogProvider.js - Provider 组件
  3. ✅ 集成到应用:
    - 修改 src/App.js，在最外层添加 <PostHogProvider>
    - 自动追踪所有页面浏览
  4. ✅ 配置环境变量:
    - 在 .env 添加 PostHog 配置项
    - REACT_APP_POSTHOG_KEY 留空，需要用户填写
  5. ✅ 创建文档: POSTHOG_INTEGRATION.md 包含完整的使用说明

src/components/PostHogProvider.js

@@ -0,0 +1,83 @@
+// src/components/PostHogProvider.js
+import React, { useEffect, useState } from 'react';
+import { initPostHog } from '../lib/posthog';
+import { usePageTracking } from '../hooks/usePageTracking';
+
+/**
+ * PostHog Provider Component
+ * Initializes PostHog SDK and provides automatic page view tracking
+ *
+ * Usage:
+ * <PostHogProvider>
+ *   <App />
+ * </PostHogProvider>
+ */
+export const PostHogProvider = ({ children }) => {
+  const [isInitialized, setIsInitialized] = useState(false);
+
+  // Initialize PostHog once when component mounts
+  useEffect(() => {
+    // Only run in browser
+    if (typeof window === 'undefined') return;
+
+    // Initialize PostHog
+    initPostHog();
+    setIsInitialized(true);
+
+    // Log initialization
+    if (process.env.NODE_ENV === 'development') {
+      console.log('✅ PostHogProvider initialized');
+    }
+  }, []);
+
+  // Automatically track page views
+  usePageTracking({
+    enabled: isInitialized,
+    getProperties: (location) => {
+      // Add custom properties based on route
+      const properties = {};
+
+      // Identify page type based on path
+      if (location.pathname === '/home' || location.pathname === '/home/') {
+        properties.page_type = 'landing';
+      } else if (location.pathname.startsWith('/home/center')) {
+        properties.page_type = 'dashboard';
+      } else if (location.pathname.startsWith('/auth/')) {
+        properties.page_type = 'auth';
+      } else if (location.pathname.startsWith('/community')) {
+        properties.page_type = 'feature';
+        properties.feature_name = 'community';
+      } else if (location.pathname.startsWith('/concepts')) {
+        properties.page_type = 'feature';
+        properties.feature_name = 'concepts';
+      } else if (location.pathname.startsWith('/stocks')) {
+        properties.page_type = 'feature';
+        properties.feature_name = 'stocks';
+      } else if (location.pathname.startsWith('/limit-analyse')) {
+        properties.page_type = 'feature';
+        properties.feature_name = 'limit_analyse';
+      } else if (location.pathname.startsWith('/trading-simulation')) {
+        properties.page_type = 'feature';
+        properties.feature_name = 'trading_simulation';
+      } else if (location.pathname.startsWith('/company')) {
+        properties.page_type = 'detail';
+        properties.content_type = 'company';
+      } else if (location.pathname.startsWith('/event-detail')) {
+        properties.page_type = 'detail';
+        properties.content_type = 'event';
+      }
+
+      return properties;
+    },
+  });
+
+  // Don't render children until PostHog is initialized
+  // This prevents tracking events before SDK is ready
+  if (!isInitialized) {
+    return children; // Or return a loading spinner
+  }
+
+  return <>{children}</>;
+};
+
+export default PostHogProvider;