refactor: context 穿透扫描生命周期，修复长驻插件阻塞和 Web Stop 无效

- RunScan 接受 context.Context，创建可取消上下文并穿透到所有策略和插件
- 长驻插件（forwardshell/socks5proxy/reverseshell）不再进入 scan WaitGroup，
  通过 ctx.Done() 管理生命周期，解除 wg.Wait() 死锁
- Web Stop API 从 stopChan 改为 context.CancelFunc，取消信号真正传播到扫描链路
- ExecuteScanTasks 和 executeScanTask 支持 context 取消检查，停止分发新任务
- CLI 模式传 context.Background()，行为完全不变

core/scanner.go

@@ -18,7 +18,7 @@ import (
 
 // ScanStrategy 定义扫描策略接口
 type ScanStrategy interface {
-	Execute(config *common.Config, state *common.State, info common.HostInfo, ch chan struct{}, wg *sync.WaitGroup)
+	Execute(ctx context.Context, config *common.Config, state *common.State, info common.HostInfo, ch chan struct{}, wg *sync.WaitGroup)
 	GetPlugins(config *common.Config) ([]string, bool)
 	IsPluginApplicableByName(pluginName string, targetHost string, targetPort int, isCustomMode bool, config *common.Config) bool
 }
@@ -73,7 +73,10 @@ func selectStrategy(config *common.Config, state *common.State, info common.Host
 }
 
 // RunScan 执行整体扫描流程
-func RunScan(info common.HostInfo, config *common.Config, state *common.State) {
+func RunScan(ctx context.Context, info common.HostInfo, config *common.Config, state *common.State) {
+	ctx, cancel := context.WithCancel(ctx)
+	defer cancel()
+
 	// 初始化HTTP客户端（静默，无需日志）
 	if err := lib.Inithttp(config); err != nil {
 		common.LogError(i18n.Tr("http_client_init_failed", err))
@@ -88,7 +91,7 @@ func RunScan(info common.HostInfo, config *common.Config, state *common.State) {
 	wg := sync.WaitGroup{}
 
 	// 执行策略
-	strategy.Execute(config, state, info, ch, &wg)
+	strategy.Execute(ctx, config, state, info, ch, &wg)
 
 	// 等待所有扫描完成
 	wg.Wait()
@@ -111,6 +114,8 @@ func RunScan(info common.HostInfo, config *common.Config, state *common.State) {
 		signal.Notify(sigChan, os.Interrupt, syscall.SIGTERM)
 		<-sigChan
 		common.LogInfo(i18n.GetText("received_exit_signal"))
+		cancel()
+		time.Sleep(500 * time.Millisecond)
 	}
 
 	// 完成扫描
@@ -134,7 +139,7 @@ func finishScan(config *common.Config, state *common.State) {
 }
 
 // ExecuteScanTasks 任务执行通用框架
-func ExecuteScanTasks(config *common.Config, state *common.State, targets []common.HostInfo, strategy ScanStrategy, ch chan struct{}, wg *sync.WaitGroup) {
+func ExecuteScanTasks(ctx context.Context, config *common.Config, state *common.State, targets []common.HostInfo, strategy ScanStrategy, ch chan struct{}, wg *sync.WaitGroup) {
 	// 获取要执行的插件
 	pluginsToRun, isCustomMode := strategy.GetPlugins(config)
 
@@ -149,6 +154,13 @@ func ExecuteScanTasks(config *common.Config, state *common.State, targets []comm
 
 	// 流式执行任务，避免预构建大量任务对象
 	for _, target := range targets {
+		// 检查取消
+		select {
+		case <-ctx.Done():
+			return
+		default:
+		}
+
 		targetPort := target.Port
 
 		for _, pluginName := range pluginsToRun {
@@ -159,7 +171,7 @@ func ExecuteScanTasks(config *common.Config, state *common.State, targets []comm
 
 			// 检查插件是否适用于当前目标
 			if strategy.IsPluginApplicableByName(pluginName, target.Host, targetPort, isCustomMode, config) {
-				executeScanTask(config, state, pluginName, target, ch, wg)
+				executeScanTask(ctx, config, state, pluginName, target, ch, wg)
 			}
 		}
 	}
@@ -182,10 +194,42 @@ func countApplicableTasks(targets []common.HostInfo, pluginsToRun []string, isCu
 	return count
 }
 
+// longRunningPlugins 长驻插件，不加入 scan WaitGroup，通过 ctx 取消退出
+var longRunningPlugins = map[string]bool{
+	"forwardshell": true,
+	"socks5proxy":  true,
+	"reverseshell": true,
+}
+
 // executeScanTask 执行单个扫描任务
-func executeScanTask(config *common.Config, state *common.State, pluginName string, target common.HostInfo, ch chan struct{}, wg *sync.WaitGroup) {
+func executeScanTask(ctx context.Context, config *common.Config, state *common.State, pluginName string, target common.HostInfo, ch chan struct{}, wg *sync.WaitGroup) {
+	// 检查取消
+	select {
+	case <-ctx.Done():
+		return
+	default:
+	}
+
+	// 长驻插件不进 WaitGroup，通过 ctx 管理生命周期
+	if longRunningPlugins[pluginName] {
+		go func() {
+			plugin := plugins.Get(pluginName)
+			if plugin != nil {
+				plugin.Scan(ctx, &target, config, state)
+			}
+		}()
+		return
+	}
+
 	wg.Add(1)
-	ch <- struct{}{} // 获取并发槽位
+
+	// 获取并发槽位，支持取消
+	select {
+	case ch <- struct{}{}:
+	case <-ctx.Done():
+		wg.Done()
+		return
+	}
 
 	go func() {
 		// 开始监控插件任务
@@ -210,7 +254,7 @@ func executeScanTask(config *common.Config, state *common.State, pluginName stri
 
 		plugin := plugins.Get(pluginName)
 		if plugin != nil {
-			result := plugin.Scan(context.Background(), &target, config, state)
+			result := plugin.Scan(ctx, &target, config, state)
 			if result != nil {
 				if result.Success {
 					// 保存成功的扫描结果到文件