feat(frontend): App 路由集成 + 木纹风格 CSS

App.tsx 添加 menu/game/replay 三页面路由切换，MainMenu 新增
onReplayStart 属性区分对局与回放入口。App.css 实现经典木纹
视觉风格（深棕底色、米黄文字、皮革纹理按钮），index.css 基础
重置。修复 tsconfig 中 erasableSyntaxOnly 无效选项并安装
@types/node。

src/App.css

@@ -1,7 +1,190 @@
+:root {
+  --bg-primary: #3C2415;
+  --bg-secondary: #F5DEB3;
+  --text-primary: #F5DEB3;
+  --text-secondary: #3C2415;
+  --accent: #8B4513;
+  --accent-hover: #A0522D;
+  --button-bg: #DEB887;
+  --button-hover: #D2B48C;
+  --border: #8B7355;
+}
+
+* {
+  margin: 0;
+  padding: 0;
+  box-sizing: border-box;
+}
+
+body {
+  font-family: 'Microsoft YaHei', sans-serif;
+  background-color: var(--bg-primary);
+  color: var(--text-primary);
+}
+
 .app {
+  width: 100vw;
+  height: 100vh;
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+}
+
+.main-menu {
   display: flex;
   flex-direction: column;
   align-items: center;
   justify-content: center;
   height: 100vh;
+  gap: 40px;
+}
+
+.menu-title {
+  font-size: 42px;
+  color: var(--text-primary);
+  text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.5);
+}
+
+.menu-buttons {
+  display: flex;
+  flex-direction: column;
+  gap: 16px;
+}
+
+.menu-buttons button {
+  width: 240px;
+  padding: 14px 28px;
+  font-size: 18px;
+  border: 2px solid var(--border);
+  border-radius: 8px;
+  background: var(--button-bg);
+  color: var(--text-secondary);
+  cursor: pointer;
+  transition: all 0.2s;
+}
+
+.menu-buttons button:hover {
+  background: var(--button-hover);
+  transform: scale(1.03);
+}
+
+.setup-panel {
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  justify-content: center;
+  height: 100vh;
+  gap: 24px;
+}
+
+.setup-panel h2 {
+  font-size: 28px;
+}
+
+.setup-panel label {
+  display: flex;
+  align-items: center;
+  gap: 8px;
+  font-size: 16px;
+}
+
+.setup-panel select, .setup-panel input {
+  padding: 6px 12px;
+  border: 1px solid var(--border);
+  border-radius: 4px;
+  background: var(--bg-secondary);
+  color: var(--text-secondary);
+  font-size: 14px;
+}
+
+.setup-actions {
+  display: flex;
+  gap: 12px;
+  margin-top: 16px;
+}
+
+button {
+  padding: 10px 24px;
+  font-size: 16px;
+  border: 2px solid var(--border);
+  border-radius: 6px;
+  background: var(--button-bg);
+  color: var(--text-secondary);
+  cursor: pointer;
+  transition: all 0.2s;
+}
+
+button:hover {
+  background: var(--button-hover);
+}
+
+button:disabled {
+  opacity: 0.5;
+  cursor: not-allowed;
+}
+
+.game-view {
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  width: 100vw;
+  height: 100vh;
+  padding: 12px;
+  gap: 8px;
+}
+
+.board-container {
+  flex: 1;
+  width: 100%;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  overflow: hidden;
+}
+
+.game-info {
+  font-size: 20px;
+  font-weight: bold;
+  padding: 8px;
+}
+
+.game-controls {
+  display: flex;
+  gap: 12px;
+  padding: 8px;
+}
+
+.timer-display {
+  font-size: 24px;
+  font-family: monospace;
+}
+
+.timer-warning {
+  color: #ff4444;
+  animation: blink 0.5s infinite alternate;
+}
+
+@keyframes blink {
+  from { opacity: 1; }
+  to { opacity: 0.3; }
+}
+
+.replay-view {
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  width: 100vw;
+  height: 100vh;
+  padding: 12px;
+  gap: 8px;
+}
+
+.step-slider {
+  width: 80%;
+  accent-color: var(--accent);
+}
+
+.replay-controls {
+  display: flex;
+  gap: 12px;
 }

src/App.tsx

@@ -1,8 +1,26 @@
+import { useState } from 'react';
+import MainMenu from './components/menu/MainMenu';
+import GameView from './components/game/GameView';
+import ReplayView from './components/replay/ReplayView';
+import './App.css';
+
+type Page = 'menu' | 'game' | 'replay';
+
 function App() {
+  const [page, setPage] = useState<Page>('menu');
+
+  const handleGameStart = () => setPage('game');
+  const handleReplayStart = () => setPage('replay');
+  const handleBackToMenu = () => setPage('menu');
+
+  if (page === 'game') return <GameView onBackToMenu={handleBackToMenu} />;
+  if (page === 'replay') return <ReplayView onBackToMenu={handleBackToMenu} />;
+
   return (
-    <div className="app">
-      <h1>五子棋 v2.0</h1>
-    </div>
+    <MainMenu
+      onGameStart={handleGameStart}
+      onReplayStart={handleReplayStart}
+    />
   );
 }
 

src/components/menu/MainMenu.tsx

@@ -9,16 +9,17 @@ type View = 'main' | 'local' | 'ai' | 'online' | 'replay';
 
 interface Props {
   onGameStart: () => void;
+  onReplayStart: () => void;
 }
 
-export default function MainMenu({ onGameStart }: Props) {
+export default function MainMenu({ onGameStart, onReplayStart }: Props) {
   const { t } = useTranslation();
   const [view, setView] = useState<View>('main');
 
   if (view === 'local') return <LocalGameSetup onBack={() => setView('main')} onStart={onGameStart} />;
   if (view === 'ai') return <AiGameSetup onBack={() => setView('main')} onStart={onGameStart} />;
   if (view === 'online') return <OnlineSetup onBack={() => setView('main')} onStart={onGameStart} />;
-  if (view === 'replay') return <LoadReplay onBack={() => setView('main')} onStart={onGameStart} />;
+  if (view === 'replay') return <LoadReplay onBack={() => setView('main')} onStart={onReplayStart} />;
 
   return (
     <div className="main-menu">