feat(assets): 优化资产预览性能并添加资源管理器连接状态提示

- 使用缩略图替代原图展示，通过 sharp 库生成缓存缩略图
- 优化资产分组逻辑，避免不必要的重计算
- 添加 WebSocket 连接状态提示到输入框
- 使用 `useCallback` 和 `useRef` 优化组件渲染性能
- 添加 AbortController 支持请求取消，防止内存泄漏
- 添加 `disconnected` 事件处理，自动重置会话状态

web/server/routes/assets.ts

@@ -76,7 +76,8 @@ assetsRouter.post('/scan', async (_req, res) => {
       manifest = JSON.parse(await fs.readFile(manifestPath, 'utf-8'));
     } catch { continue; }
 
-    const accountId = manifest.account?.id || '';
+    const accountId = typeof manifest.account === 'string' ? manifest.account
+      : manifest.account?.id || '';
 
     // Scan images
     const imagesDir = path.join(outputDir, dir.name, 'images');
@@ -131,5 +132,35 @@ assetsRouter.get('/file', (req, res) => {
   const fullPath = path.resolve(PROJECT_ROOT, filePath);
   if (!fullPath.startsWith(PROJECT_ROOT)) return res.status(403).send('Forbidden');
   if (!fss.existsSync(fullPath)) return res.status(404).send('Not found');
+  // Cache static assets for 1 hour
+  res.setHeader('Cache-Control', 'public, max-age=3600');
   res.sendFile(fullPath);
 });
+
+// Serve resized thumbnail for images
+assetsRouter.get('/thumb', async (req, res) => {
+  const filePath = req.query.path as string;
+  const size = Math.min(parseInt(req.query.size as string) || 200, 400);
+  if (!filePath) return res.status(400).send('Missing path');
+  const fullPath = path.resolve(PROJECT_ROOT, filePath);
+  if (!fullPath.startsWith(PROJECT_ROOT)) return res.status(403).send('Forbidden');
+  if (!fss.existsSync(fullPath)) return res.status(404).send('Not found');
+
+  // For non-images, redirect to full file
+  if (!/\.(jpe?g|png|webp)$/i.test(fullPath)) {
+    return res.redirect(`/api/assets/file?path=${encodeURIComponent(filePath)}`);
+  }
+
+  try {
+    const sharp = (await import('sharp')).default;
+    const buffer = await sharp(fullPath)
+      .resize(size, size, { fit: 'cover' })
+      .jpeg({ quality: 70 })
+      .toBuffer();
+    res.setHeader('Cache-Control', 'public, max-age=86400');
+    res.setHeader('Content-Type', 'image/jpeg');
+    res.send(buffer);
+  } catch {
+    res.sendFile(fullPath);
+  }
+});