feat: 添加 Admin Dashboard — React 19 SPA，包含 7 个页面

- Dashboard: 健康状态轮询、状态卡片、内存统计、快捷操作
- Login: 二维码展示 + 3 秒自动轮询 + 倒计时 + 登出
- Browser: 探索/搜索/用户三标签页，Feed 网格、详情面板、评论树
- Publish: 图文/视频发布表单，支持标签、可见性、定时发布
- Interactions: 点赞/取消点赞、收藏、评论、回复 + 操作日志
- API Tester: 端点选择器、请求体编辑器、cURL 生成、响应查看、历史记录
- Settings: Token 配置、服务器 URL 设置

后端改动:
- app.ts: 生产环境提供 dist/web/ 静态文件服务 + SPA fallback
- Dockerfile: 添加 web 构建阶段
- package.json: 添加 build:web、build:all、dev:web 脚本

技术栈: React 19 + TypeScript + Vite 6 + Tailwind CSS（暗色主题）
产物: 85.5 KB gzip JS + 4 KB gzip CSS，零重型依赖

src/server/app.ts

@@ -1,4 +1,7 @@
 import http from 'node:http';
+import path from 'node:path';
+import { fileURLToPath } from 'node:url';
+import fs from 'node:fs';
 
 import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js';
 import { SSEServerTransport } from '@modelcontextprotocol/sdk/server/sse.js';
@@ -147,6 +150,9 @@ export class AppServer {
       }
     }
 
+    // Serve the web dashboard (static SPA) in production.
+    this.setupWebDashboard();
+
     // Re-register the error handler so it sits after any plugin routes.
     this.app.use(errorHandler);
 
@@ -290,6 +296,46 @@ export class AppServer {
     });
   }
 
+  // -- Private: Web Dashboard (SPA static files) ----------------------------
+
+  private setupWebDashboard(): void {
+    // Resolve the web dashboard dist directory relative to this file.
+    // In the built output: dist/server/app.js → dist/web/ is at ../web
+    const thisDir = path.dirname(fileURLToPath(import.meta.url));
+    const webDir = path.resolve(thisDir, '..', 'web');
+
+    if (!fs.existsSync(webDir)) {
+      logger.debug({ webDir }, 'Web dashboard dist not found, skipping static mount');
+      return;
+    }
+
+    logger.info({ webDir }, 'Mounting web dashboard');
+
+    // Serve static assets
+    this.app.use(express.static(webDir, { index: false }));
+
+    // SPA fallback: any GET that doesn't match /api, /sse, /messages, /health
+    // returns index.html so client-side routing works.
+    this.app.get('*', (req, res, next) => {
+      // Skip API / MCP / health routes
+      if (
+        req.path.startsWith('/api') ||
+        req.path.startsWith('/sse') ||
+        req.path.startsWith('/messages') ||
+        req.path === '/health'
+      ) {
+        next();
+        return;
+      }
+      const indexPath = path.join(webDir, 'index.html');
+      if (fs.existsSync(indexPath)) {
+        res.sendFile(indexPath);
+      } else {
+        next();
+      }
+    });
+  }
+
   private async buildHealthResponse(): Promise<Record<string, unknown>> {
     // Memory usage
     const mem = process.memoryUsage();