feat(claude): 实现智能请求头管理系统

核心功能:
- 支持渠道级透传设置 (修复 killcode 客户端兼容性)
- 智能客户端检测 (Claude Code、killcode、其他客户端)
- 动态请求头策略 (透传 vs 伪装)

客户端处理策略:
- Claude Code (claude-cli/*): 完全透传原始请求头
- killcode (B2/JS + Stainless SDK): 完全透传原始请求头
- 其他客户端: 伪装成 killcode 格式绕过上游限制

技术改进:
- 防止显示 Go-http-client/2.0 User-Agent
- 保留重要认证头部 (anthropic-version, anthropic-beta)
- 兼容全局透传和渠道透传设置

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

relay/channel/claude/adaptor.go

@@ -61,15 +61,28 @@ func (a *Adaptor) GetRequestURL(info *relaycommon.RelayInfo) (string, error) {
 
 func (a *Adaptor) SetupRequestHeader(c *gin.Context, req *http.Header, info *relaycommon.RelayInfo) error {
 	if model_setting.GetGlobalSettings().PassThroughRequestEnabled || info.ChannelSetting.PassThroughBodyEnabled {
-		// 穿透模式：直接复制原始请求头，但跳过系统级头信息
-		for key, values := range c.Request.Header {
-			keyLower := strings.ToLower(key)
-			if keyLower == "host" || keyLower == "content-length" || keyLower == "connection" {
-				continue
-			}
-			for _, value := range values {
-				req.Add(key, value)
+		userAgent := c.Request.Header.Get("User-Agent")
+		
+		// 智能请求头策略：检测客户端类型并决定处理方式
+		if isClaudeCode(userAgent) || isKillcode(userAgent) {
+			// Claude Code 和 killcode: 完全透传原始请求头
+			for key, values := range c.Request.Header {
+				keyLower := strings.ToLower(key)
+				if keyLower == "host" || keyLower == "content-length" || keyLower == "connection" {
+					continue
+				}
+				for _, value := range values {
+					req.Add(key, value)
+				}
 			}
+		} else {
+			// 其他客户端: 伪装成 killcode 格式以绕过上游限制
+			setupKillcodeHeaders(c, req)
+		}
+		
+		// 保险：确保 User-Agent 一定存在，避免显示 Go-http-client/2.0
+		if req.Get("User-Agent") == "" {
+			req.Set("User-Agent", "B2/JS 0.51.0")
 		}
 	} else {
 		// 非穿透模式：使用通用设置
@@ -79,7 +92,7 @@ func (a *Adaptor) SetupRequestHeader(c *gin.Context, req *http.Header, info *rel
 	// 无论哪种模式都需要设置正确的API密钥
 	req.Set("x-api-key", info.ApiKey)
 	
-	if !model_setting.GetGlobalSettings().PassThroughRequestEnabled {
+	if !model_setting.GetGlobalSettings().PassThroughRequestEnabled && !info.ChannelSetting.PassThroughBodyEnabled {
 		// 非穿透模式才强制设置这些头
 		anthropicVersion := c.Request.Header.Get("anthropic-version")
 		if anthropicVersion == "" {
@@ -91,6 +104,51 @@ func (a *Adaptor) SetupRequestHeader(c *gin.Context, req *http.Header, info *rel
 	return nil
 }
 
+// isClaudeCode 检测是否为 Claude Code 客户端
+func isClaudeCode(userAgent string) bool {
+	return strings.Contains(userAgent, "claude-cli")
+}
+
+// isKillcode 检测是否为 killcode 客户端
+func isKillcode(userAgent string) bool {
+	return strings.Contains(userAgent, "B2/JS") || strings.Contains(userAgent, "X-Stainless")
+}
+
+// setupKillcodeHeaders 设置 killcode 风格的请求头，用于伪装其他客户端
+func setupKillcodeHeaders(c *gin.Context, req *http.Header) {
+	// 基础头部
+	req.Set("User-Agent", "B2/JS 0.51.0")
+	req.Set("Connection", "keep-alive")
+	req.Set("Accept", "application/json")
+	req.Set("Accept-Encoding", "br, gzip, deflate")
+	req.Set("Content-Type", "application/json")
+	
+	// Stainless SDK 特有头部
+	req.Set("X-Stainless-Retry-Count", "0")
+	req.Set("X-Stainless-Timeout", "600")
+	req.Set("X-Stainless-Lang", "js")
+	req.Set("X-Stainless-Package-Version", "0.51.0")
+	req.Set("X-Stainless-OS", "Windows")
+	req.Set("X-Stainless-Arch", "x64")
+	req.Set("X-Stainless-Runtime", "node")
+	req.Set("X-Stainless-Runtime-Version", "v20.19.1")
+	
+	// 保留重要的原始头部
+	if anthropicVersion := c.Request.Header.Get("anthropic-version"); anthropicVersion != "" {
+		req.Set("anthropic-version", anthropicVersion)
+	} else {
+		req.Set("anthropic-version", "2023-06-01")
+	}
+	
+	if anthropicBeta := c.Request.Header.Get("anthropic-beta"); anthropicBeta != "" {
+		req.Set("anthropic-beta", anthropicBeta)
+	}
+	
+	// 其他辅助头部
+	req.Set("accept-language", "*")
+	req.Set("sec-fetch-mode", "cors")
+}
+
 func (a *Adaptor) ConvertOpenAIRequest(c *gin.Context, info *relaycommon.RelayInfo, request *dto.GeneralOpenAIRequest) (any, error) {
 	if request == nil {
 		return nil, errors.New("request is nil")