feat: 统一服务缓存 + 指纹驱动插件匹配

将 webServiceCache 扩展为通用 serviceCache，所有指纹识别结果
统一缓存，插件匹配时端口不命中则回退到服务名称匹配。

删除多余的 service_cache.go，复用已有的 ServiceInfo 体系。
补充 nil 防御、Explicit 标记、大量单元/集成/回归测试。

core/tuning_cli_integration_test.go

@@ -0,0 +1,82 @@
+package core
+
+import (
+	"flag"
+	"os"
+	"testing"
+	"time"
+
+	"github.com/shadow1ng/fscan/common"
+)
+
+func TestCLIExplicitDefaultTuningFlagsSurviveTuneConfig(t *testing.T) {
+	oldArgs := os.Args
+	oldFlagSet := flag.CommandLine
+	oldFlagVars := *common.GetFlagVars()
+	defer func() {
+		os.Args = oldArgs
+		flag.CommandLine = oldFlagSet
+		*common.GetFlagVars() = oldFlagVars
+	}()
+
+	*common.GetFlagVars() = common.FlagVars{}
+	flag.CommandLine = flag.NewFlagSet("fscan-test", flag.ContinueOnError)
+	os.Args = []string{
+		"fscan-test",
+		"-silent",
+		"-h", "127.0.0.1",
+		"-time", "3",
+		"-mt", "20",
+		"-retry", "3",
+		"-icmp-rate", "0.1",
+		"-num", "20",
+	}
+
+	info := &common.HostInfo{}
+	if err := common.Flag(info); err != nil {
+		t.Fatalf("Flag error = %v", err)
+	}
+
+	cfg, _, err := common.BuildConfig(common.GetFlagVars(), info)
+	if err != nil {
+		t.Fatalf("BuildConfig error = %v", err)
+	}
+	if !cfg.TimeoutExplicit || !cfg.ModuleThreadNumExplicit ||
+		!cfg.MaxRetriesExplicit || !cfg.Network.ICMPRateExplicit ||
+		!cfg.POC.NumExplicit {
+		t.Fatalf("explicit flags not propagated: timeout=%v mt=%v retry=%v icmp=%v num=%v",
+			cfg.TimeoutExplicit,
+			cfg.ModuleThreadNumExplicit,
+			cfg.MaxRetriesExplicit,
+			cfg.Network.ICMPRateExplicit,
+			cfg.POC.NumExplicit)
+	}
+
+	ep := &EnvironmentProfile{
+		Net: NetworkProfile{
+			Env:       EnvLAN,
+			RTTMedian: time.Millisecond,
+			RTTStddev: 200 * time.Microsecond,
+			LossRate:  0,
+			Samples:   30,
+		},
+		System: SystemProfile{FDLimit: 65536, NumCPU: 8},
+	}
+	ep.TuneConfig(cfg, makeTestSession(cfg))
+
+	if cfg.Timeout != 3*time.Second {
+		t.Fatalf("Timeout = %v, want explicit default 3s", cfg.Timeout)
+	}
+	if cfg.ModuleThreadNum != 20 {
+		t.Fatalf("ModuleThreadNum = %d, want explicit default 20", cfg.ModuleThreadNum)
+	}
+	if cfg.MaxRetries != 3 {
+		t.Fatalf("MaxRetries = %d, want explicit default 3", cfg.MaxRetries)
+	}
+	if cfg.Network.ICMPRate != 0.1 {
+		t.Fatalf("ICMPRate = %.2f, want explicit default 0.10", cfg.Network.ICMPRate)
+	}
+	if cfg.POC.Num != 20 {
+		t.Fatalf("POC.Num = %d, want explicit default 20", cfg.POC.Num)
+	}
+}