feat: React app shell with global styles and state-based routing (Task 8)

- index.css: brand CSS custom properties, .btn, input styles, .app-shell layout
- App.tsx: session token extraction from URL, /api/auth/me validation, 4-route shell
- main.tsx: renders App with StrictMode

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

client/src/App.tsx

@@ -0,0 +1,85 @@
+import { useState, useEffect } from 'react'
+import './index.css'
+
+type Route = 'login' | 'onboarding' | 'game' | 'admin'
+
+export default function App() {
+  const [route, setRoute] = useState<Route>('login')
+  const [sessionToken, setSessionToken] = useState<string | null>(null)
+  const [loading, setLoading] = useState(true)
+
+  useEffect(() => {
+    // 1. Check for ?session=<token> in URL (from magic link redirect)
+    const params = new URLSearchParams(window.location.search)
+    const urlToken = params.get('session')
+    if (urlToken) {
+      localStorage.setItem('session', urlToken)
+      window.history.replaceState({}, '', window.location.pathname)
+    }
+
+    // 2. Try stored token
+    const stored = urlToken || localStorage.getItem('session')
+    if (!stored) { setLoading(false); return }
+
+    // 3. Validate token with /api/auth/me
+    fetch('/api/auth/me', {
+      headers: { Authorization: `Bearer ${stored}` },
+    })
+      .then(r => {
+        if (r.ok) {
+          setSessionToken(stored)
+          // TODO in Task 9: check if onboarding complete, route accordingly
+          setRoute('game')
+        } else {
+          localStorage.removeItem('session')
+        }
+      })
+      .catch(() => localStorage.removeItem('session'))
+      .finally(() => setLoading(false))
+  }, [])
+
+  if (loading) {
+    return (
+      <div className="app-shell" style={{ textAlign: 'center', paddingTop: '4rem' }}>
+        <p style={{ fontFamily: 'var(--font-header)', color: 'var(--color-forest)' }}>
+          Loading quest...
+        </p>
+      </div>
+    )
+  }
+
+  return (
+    <div className="app-shell">
+      {route === 'login' && (
+        <div>
+          <h1 style={{ marginBottom: '1rem' }}>MorseQuest</h1>
+          <p>Login page coming in Task 9.</p>
+          <button className="btn" onClick={() => setRoute('game')}>
+            Continue as Guest (dev)
+          </button>
+        </div>
+      )}
+      {route === 'onboarding' && (
+        <div>
+          <h1>Onboarding</h1>
+          <p>Mnemonic builder coming in Task 10.</p>
+        </div>
+      )}
+      {route === 'game' && (
+        <div>
+          <h1>Practice</h1>
+          <p>Game loop coming in Task 11.</p>
+          <button className="btn" onClick={() => { localStorage.removeItem('session'); setRoute('login') }}>
+            Log out
+          </button>
+        </div>
+      )}
+      {route === 'admin' && (
+        <div>
+          <h1>Admin</h1>
+          <p>Admin panel coming in Task 12.</p>
+        </div>
+      )}
+    </div>
+  )
+}

client/src/index.css

@@ -0,0 +1,63 @@
+/* CSS custom properties */
+:root {
+  --color-gold: #D4AF37;
+  --color-blue: #4169E1;
+  --color-parchment: #F5E6D3;
+  --color-forest: #3C2415;
+  --color-brown: #654321;
+  --font-header: 'Cinzel', serif;
+  --font-body: 'Open Sans', sans-serif;
+  --font-mono: 'Source Code Pro', monospace;
+}
+
+/* Reset + base */
+*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
+body {
+  font-family: var(--font-body);
+  background: var(--color-parchment);
+  color: var(--color-forest);
+  min-height: 100vh;
+}
+
+/* Typography */
+h1, h2, h3 { font-family: var(--font-header); color: var(--color-forest); }
+code, .mono { font-family: var(--font-mono); }
+
+/* Shared button style */
+.btn {
+  display: inline-block;
+  padding: 0.7rem 1.6rem;
+  background: var(--color-gold);
+  color: var(--color-forest);
+  border: 2px solid var(--color-forest);
+  font-family: var(--font-header);
+  font-size: 1rem;
+  font-weight: 600;
+  cursor: pointer;
+  text-decoration: none;
+}
+.btn:hover { background: var(--color-forest); color: var(--color-parchment); }
+.btn-ghost {
+  background: transparent;
+  border-color: var(--color-gold);
+  color: var(--color-forest);
+}
+
+/* Input */
+input[type="text"], input[type="email"] {
+  width: 100%;
+  padding: 0.6rem 0.8rem;
+  border: 2px solid var(--color-brown);
+  background: white;
+  font-family: var(--font-body);
+  font-size: 1rem;
+  color: var(--color-forest);
+}
+input:focus { outline: 2px solid var(--color-gold); outline-offset: 1px; }
+
+/* Layout shell */
+.app-shell {
+  max-width: 680px;
+  margin: 0 auto;
+  padding: 1rem;
+}

client/src/main.tsx

@@ -1,8 +1,10 @@
 import React from 'react'
 import ReactDOM from 'react-dom/client'
+import './index.css'
+import App from './App'
 
 ReactDOM.createRoot(document.getElementById('root')!).render(
   <React.StrictMode>
-    <div>MorseQuest loading...</div>
+    <App />
   </React.StrictMode>
 )