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/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">