feat(sync): full code sync from release

backend/internal/service/claude_code_validator.go

@@ -78,7 +78,7 @@ func (v *ClaudeCodeValidator) Validate(r *http.Request, body map[string]any) boo
 
 	// Step 3: 检查 max_tokens=1 + haiku 探测请求绕过
 	// 这类请求用于 Claude Code 验证 API 连通性，不携带 system prompt
-	if isMaxTokensOneHaiku, ok := r.Context().Value(ctxkey.IsMaxTokensOneHaikuRequest).(bool); ok && isMaxTokensOneHaiku {
+	if isMaxTokensOneHaiku, ok := IsMaxTokensOneHaikuRequestFromContext(r.Context()); ok && isMaxTokensOneHaiku {
 		return true // 绕过 system prompt 检查，UA 已在 Step 1 验证
 	}