fix: division by zero guard, logout redirect, onboarding close button

- auto_trader_risk: skip drawdown check when entryPrice <= 0
- AuthContext: redirect to / on logout
- App.tsx: simplify data page navigation
- BeginnerOnboardingPage: add close button to overlay

web/src/App.tsx

@@ -451,19 +451,7 @@ function App() {
   // Data page - publicly accessible with embedded dashboard
   if (route === '/data') {
     const dataPageNavigate = (page: Page) => {
-      const pathMap: Record<string, string> = {
-        'data': '/data',
-        'competition': '/competition',
-        'strategy-market': '/strategy-market',
-        'traders': '/traders',
-        'trader': '/dashboard',
-        'strategy': '/strategy',
-        'faq': '/faq',
-      }
-      const path = pathMap[page]
-      if (path) {
-        window.location.href = path
-      }
+      navigateToPage(page)
     }
     return (
       <div

web/src/contexts/AuthContext.tsx

@@ -290,6 +290,8 @@ export function AuthProvider({ children }: { children: React.ReactNode }) {
     setToken(null)
     localStorage.removeItem('auth_token')
     localStorage.removeItem('auth_user')
+    window.history.pushState({}, '', '/')
+    window.dispatchEvent(new PopStateEvent('popstate'))
   }
 
   return (

web/src/pages/BeginnerOnboardingPage.tsx

@@ -5,6 +5,7 @@ import {
   RefreshCw,
   Shield,
   Wallet,
+  X,
 } from 'lucide-react'
 import { QRCodeSVG } from 'qrcode.react'
 import { toast } from 'sonner'
@@ -85,6 +86,14 @@ export function BeginnerOnboardingPage() {
     <div className="fixed inset-0 z-[80]">
       <div className="absolute inset-0 bg-black/58 backdrop-blur-[2px]" />
       <div className="relative flex min-h-screen items-center justify-center px-4 py-10 sm:px-6">
+        <button
+          type="button"
+          onClick={handleContinue}
+          className="absolute right-6 top-6 z-10 inline-flex h-10 w-10 items-center justify-center rounded-full border border-white/10 bg-white/5 text-zinc-400 transition hover:border-white/20 hover:bg-white/10 hover:text-white"
+          aria-label={isZh ? '跳过' : 'Skip'}
+        >
+          <X className="h-5 w-5" />
+        </button>
         <div className="w-full max-w-[1120px]">
           <div className="mb-5 flex flex-col gap-4 lg:flex-row lg:items-end lg:justify-between">
             <div className="flex items-center gap-4">