feat: v2.1.0 核心重构与功能增强

## 架构重构
- 全局变量消除，迁移至 Config/State 对象
- SMB 插件融合（smb/smb2/smbghost/smbinfo）
- 服务探测重构，实现 Nmap 风格 fallback 机制
- 输出系统重构，TXT 实时刷盘 + 双写机制
- i18n 框架升级至 go-i18n

## 性能优化
- 正则表达式预编译
- 内存优化 map[string]struct{}
- 并发指纹匹配
- SOCKS5 连接复用
- 滑动窗口调度 + 自适应线程池

## 新功能
- Web 管理界面
- 多格式 POC 适配（xray/afrog）
- 增强指纹库（3139条）
- Favicon hash 指纹识别
- 插件选择性编译（Build Tags）
- fscan-lab 靶场环境
- 默认端口扩展（62→133）

## 构建系统
- 添加 no_local tag 支持排除本地插件
- 多版本构建：fscan/fscan-nolocal/fscan-web
- CI 添加 snapshot 模式支持仅测试构建

## Bug 修复
- 修复 120+ 个问题，包括 RDP panic、批量扫描漏报、
  JSON 输出格式、Redis 检测、Context 超时等

## 测试增强
- 单元测试覆盖率 74-100%
- 并发安全测试
- 集成测试（Web/端口/服务/SSH/ICMP）

plugins/services/elasticsearch.go

@@ -0,0 +1,135 @@
+//go:build plugin_elasticsearch || !plugin_selective
+
+package services
+
+import (
+	"context"
+	"crypto/tls"
+	"encoding/base64"
+	"fmt"
+	"io"
+	"net/http"
+
+	"github.com/shadow1ng/fscan/common"
+	"github.com/shadow1ng/fscan/common/i18n"
+	"github.com/shadow1ng/fscan/plugins"
+)
+
+type ElasticsearchPlugin struct {
+	plugins.BasePlugin
+}
+
+func NewElasticsearchPlugin() *ElasticsearchPlugin {
+	return &ElasticsearchPlugin{
+		BasePlugin: plugins.NewBasePlugin("elasticsearch"),
+	}
+}
+
+func (p *ElasticsearchPlugin) Scan(ctx context.Context, info *common.HostInfo, config *common.Config, state *common.State) *ScanResult {
+	target := info.Target()
+
+	if config.DisableBrute {
+		return p.identifyService(ctx, info, config, state)
+	}
+
+	credentials := GenerateCredentials("elasticsearch", config)
+	if len(credentials) == 0 {
+		return &ScanResult{
+			Success: false,
+			Service: "elasticsearch",
+			Error:   fmt.Errorf("没有可用的测试凭据"),
+		}
+	}
+
+	for _, cred := range credentials {
+		if p.testCredential(ctx, info, cred, config, state) {
+			common.LogSuccess(i18n.Tr("elasticsearch_credential", target, cred.Username, cred.Password))
+			return &ScanResult{
+				Success:  true,
+					Type:     plugins.ResultTypeCredential,
+				Service:  "elasticsearch",
+				Username: cred.Username,
+				Password: cred.Password,
+			}
+		}
+	}
+
+	return &ScanResult{
+		Success: false,
+		Service: "elasticsearch",
+		Error:   fmt.Errorf("未发现弱密码"),
+	}
+}
+
+func (p *ElasticsearchPlugin) testCredential(ctx context.Context, info *common.HostInfo, cred Credential, config *common.Config, state *common.State) bool {
+	client := &http.Client{
+		Timeout: config.Timeout,
+		Transport: &http.Transport{
+			TLSClientConfig: &tls.Config{InsecureSkipVerify: true},
+		},
+	}
+
+	// 构建URL
+	protocol := "http"
+	if info.Port == 9443 {
+		protocol = "https"
+	}
+	url := fmt.Sprintf("%s://%s:%d/", protocol, info.Host, info.Port)
+
+	req, err := http.NewRequestWithContext(ctx, "GET", url, nil)
+	if err != nil {
+		return false
+	}
+
+	if cred.Username != "" || cred.Password != "" {
+		auth := base64.StdEncoding.EncodeToString([]byte(cred.Username + ":" + cred.Password))
+		req.Header.Set("Authorization", "Basic "+auth)
+	}
+
+	resp, err := client.Do(req)
+	if err != nil {
+		state.IncrementTCPFailedPacketCount()
+		return false
+	}
+	state.IncrementTCPSuccessPacketCount()
+	defer func() { _ = resp.Body.Close() }()
+
+	if resp.StatusCode == 200 {
+		body, err := io.ReadAll(resp.Body)
+		if err != nil {
+			return false
+		}
+
+		bodyStr := string(body)
+		return common.ContainsAny(bodyStr, "elasticsearch", "cluster_name")
+	}
+
+	return false
+}
+
+func (p *ElasticsearchPlugin) identifyService(ctx context.Context, info *common.HostInfo, config *common.Config, state *common.State) *ScanResult {
+	target := info.Target()
+
+	if p.testCredential(ctx, info, Credential{Username: "", Password: ""}, config, state) {
+		banner := "Elasticsearch"
+		common.LogSuccess(i18n.Tr("elasticsearch_service", target, banner))
+		return &ScanResult{
+			Success: true,
+				Type:     plugins.ResultTypeService,
+			Service: "elasticsearch",
+			Banner:  banner,
+		}
+	}
+	return &ScanResult{
+		Success: false,
+		Service: "elasticsearch",
+		Error:   fmt.Errorf("无法识别为Elasticsearch服务"),
+	}
+}
+
+func init() {
+	// 使用高效注册方式：直接传递端口信息，避免实例创建
+	RegisterPluginWithPorts("elasticsearch", func() Plugin {
+		return NewElasticsearchPlugin()
+	}, []int{9200, 9300})
+}