feat: 添加 -nsp 参数禁用网段预筛

大规模扫描时 probeSubnets 会自动跳过空 /24 网段，
部分场景下用户需要关闭此优化以扫描全部目标。
新增 -nsp (no subnet probe) 参数控制。

pkg/fscan/scanner.go

@@ -411,6 +411,7 @@ func buildFlagVars(config Config, target Target) *common.FlagVars {
 		GlobalTimeout:       180,
 		DisablePing:         config.DisablePing,
 		DisableTcpProbe:     config.DisableTCPProbe,
+		DisableSubnetProbe:  config.DisableSubnetProbe,
 		AliveOnly:           false,
 		DisableBrute:        config.DisableBrute,
 		MaxRetries:          maxRetries,

pkg/fscan/types.go

@@ -133,9 +133,10 @@ type Config struct {
 	ModuleThreads int
 	MaxRetries    int
 
-	DisablePing     bool
-	DisableTCPProbe bool
-	DisableBrute    bool
+	DisablePing        bool
+	DisableTCPProbe    bool
+	DisableSubnetProbe bool
+	DisableBrute       bool
 
 	Usernames       []string
 	Passwords       []string