下载模组更新，新增下载组件，下载监听改为全局，全量改为增量监听

backend/services/progress-manager.js

@@ -5,6 +5,10 @@ class ProgressManager {
   constructor() {
     // 进度监听器: taskId -> listeners[]
     this.progressListeners = new Map();
+    // 节流控制: taskId -> { lastUpdate, pending }
+    this.throttleControl = new Map();
+    // 节流间隔（毫秒）
+    this.throttleInterval = 100;
   }
 
   /**
@@ -29,14 +33,56 @@ class ProgressManager {
       }
       if (listeners.length === 0) {
         this.progressListeners.delete(taskId);
+        // 清理节流控制
+        this.throttleControl.delete(taskId);
       }
     }
   }
 
   /**
-   * 通知进度更新
+   * 通知进度更新（带节流）
    */
   notifyProgressUpdate(taskId, task) {
+    if (!this.progressListeners.has(taskId)) {
+      return;
+    }
+
+    const now = Date.now();
+    const throttleInfo = this.throttleControl.get(taskId);
+
+    // 如果是重要状态变更（完成、失败、取消），立即通知
+    const isImportantStatus = ['completed', 'failed', 'cancelled', 'partial', 'paused'].includes(task.status);
+    
+    if (isImportantStatus) {
+      // 立即通知重要状态变更
+      this._executeListeners(taskId, task);
+      // 清理节流控制
+      this.throttleControl.delete(taskId);
+      return;
+    }
+
+    // 对于普通进度更新，使用节流
+    if (!throttleInfo || (now - throttleInfo.lastUpdate) >= this.throttleInterval) {
+      // 立即通知
+      this._executeListeners(taskId, task);
+      this.throttleControl.set(taskId, { lastUpdate: now, pending: false });
+    } else if (!throttleInfo.pending) {
+      // 延迟通知
+      throttleInfo.pending = true;
+      setTimeout(() => {
+        const currentThrottleInfo = this.throttleControl.get(taskId);
+        if (currentThrottleInfo && currentThrottleInfo.pending) {
+          this._executeListeners(taskId, task);
+          this.throttleControl.delete(taskId);
+        }
+      }, this.throttleInterval - (now - throttleInfo.lastUpdate));
+    }
+  }
+
+  /**
+   * 执行监听器（内部方法）
+   */
+  _executeListeners(taskId, task) {
     if (this.progressListeners.has(taskId)) {
       const listeners = this.progressListeners.get(taskId);
       listeners.forEach(listener => {