refactor: 引入 ScanSession，替代全局状态穿透扫描管道 (Phase 1-3)

- 新增 common/session.go: ScanSession 结构体封装 Config/State/Params/Dialer
- RunScan/Strategy/ExecuteScanTasks/executeScanTask 全部接收 session
- Plugin 接口从 Scan(ctx, info, config, state) 改为 Scan(ctx, info, session)
- 48 个插件实现统一更新签名
- Web API 构建 ScanSession 传给 RunScan
- CLI 模式通过 Initialize() 创建 session

plugins/local/shellenv.go

@@ -33,7 +33,8 @@ func NewShellEnvPlugin() *ShellEnvPlugin {
 }
 
 // Scan 执行Shell环境变量持久化 - 直接实现
-func (p *ShellEnvPlugin) Scan(ctx context.Context, info *common.HostInfo, config *common.Config, state *common.State) *plugins.Result {
+func (p *ShellEnvPlugin) Scan(ctx context.Context, info *common.HostInfo, session *common.ScanSession) *plugins.Result {
+	config := session.Config
 	var output strings.Builder
 
 	if runtime.GOOS != "linux" {