feat(gateway): 添加流超时处理机制

- 添加 StreamTimeoutSettings 配置结构体和系统设置
- 实现 TimeoutCounterCache Redis 计数器用于累计超时次数
- 在 RateLimitService 添加 HandleStreamTimeout 方法
- 在 gateway_service、openai_gateway_service、antigravity_gateway_service 中调用超时处理
- 添加后端 API 端点 GET/PUT /admin/settings/stream-timeout
- 添加前端配置界面到系统设置页面
- 支持配置：启用开关、超时阈值、处理方式、暂停时长、触发阈值、阈值窗口

默认配置：
- 启用：true
- 超时阈值：60秒
- 处理方式：临时不可调度
- 暂停时长：5分钟
- 触发阈值：3次
- 阈值窗口：10分钟

backend/internal/service/ratelimit_service.go

@@ -15,13 +15,15 @@ import (
 
 // RateLimitService 处理限流和过载状态管理
 type RateLimitService struct {
-	accountRepo        AccountRepository
-	usageRepo          UsageLogRepository
-	cfg                *config.Config
-	geminiQuotaService *GeminiQuotaService
-	tempUnschedCache   TempUnschedCache
-	usageCacheMu       sync.RWMutex
-	usageCache         map[int64]*geminiUsageCacheEntry
+	accountRepo         AccountRepository
+	usageRepo           UsageLogRepository
+	cfg                 *config.Config
+	geminiQuotaService  *GeminiQuotaService
+	tempUnschedCache    TempUnschedCache
+	timeoutCounterCache TimeoutCounterCache
+	settingService      *SettingService
+	usageCacheMu        sync.RWMutex
+	usageCache          map[int64]*geminiUsageCacheEntry
 }
 
 type geminiUsageCacheEntry struct {
@@ -44,6 +46,16 @@ func NewRateLimitService(accountRepo AccountRepository, usageRepo UsageLogReposi
 	}
 }
 
+// SetTimeoutCounterCache 设置超时计数器缓存（可选依赖）
+func (s *RateLimitService) SetTimeoutCounterCache(cache TimeoutCounterCache) {
+	s.timeoutCounterCache = cache
+}
+
+// SetSettingService 设置系统设置服务（可选依赖）
+func (s *RateLimitService) SetSettingService(settingService *SettingService) {
+	s.settingService = settingService
+}
+
 // HandleUpstreamError 处理上游错误响应，标记账号状态
 // 返回是否应该停止该账号的调度
 func (s *RateLimitService) HandleUpstreamError(ctx context.Context, account *Account, statusCode int, headers http.Header, responseBody []byte) (shouldDisable bool) {
@@ -555,3 +567,125 @@ func truncateTempUnschedMessage(body []byte, maxBytes int) string {
 	}
 	return strings.TrimSpace(string(body))
 }
+
+// HandleStreamTimeout 处理流数据超时
+// 根据系统设置决定是否标记账户为临时不可调度或错误状态
+// 返回是否应该停止该账号的调度
+func (s *RateLimitService) HandleStreamTimeout(ctx context.Context, account *Account, model string) bool {
+	if account == nil {
+		return false
+	}
+
+	// 获取系统设置
+	if s.settingService == nil {
+		log.Printf("[StreamTimeout] settingService not configured, skipping timeout handling for account %d", account.ID)
+		return false
+	}
+
+	settings, err := s.settingService.GetStreamTimeoutSettings(ctx)
+	if err != nil {
+		log.Printf("[StreamTimeout] Failed to get settings: %v", err)
+		return false
+	}
+
+	if !settings.Enabled {
+		return false
+	}
+
+	if settings.Action == StreamTimeoutActionNone {
+		return false
+	}
+
+	// 增加超时计数
+	var count int64 = 1
+	if s.timeoutCounterCache != nil {
+		count, err = s.timeoutCounterCache.IncrementTimeoutCount(ctx, account.ID, settings.ThresholdWindowMinutes)
+		if err != nil {
+			log.Printf("[StreamTimeout] Failed to increment timeout count for account %d: %v", account.ID, err)
+			// 继续处理，使用 count=1
+			count = 1
+		}
+	}
+
+	log.Printf("[StreamTimeout] Account %d timeout count: %d/%d (window: %d min, model: %s)",
+		account.ID, count, settings.ThresholdCount, settings.ThresholdWindowMinutes, model)
+
+	// 检查是否达到阈值
+	if count < int64(settings.ThresholdCount) {
+		return false
+	}
+
+	// 达到阈值，执行相应操作
+	switch settings.Action {
+	case StreamTimeoutActionTempUnsched:
+		return s.triggerStreamTimeoutTempUnsched(ctx, account, settings, model)
+	case StreamTimeoutActionError:
+		return s.triggerStreamTimeoutError(ctx, account, model)
+	default:
+		return false
+	}
+}
+
+// triggerStreamTimeoutTempUnsched 触发流超时临时不可调度
+func (s *RateLimitService) triggerStreamTimeoutTempUnsched(ctx context.Context, account *Account, settings *StreamTimeoutSettings, model string) bool {
+	now := time.Now()
+	until := now.Add(time.Duration(settings.TempUnschedMinutes) * time.Minute)
+
+	state := &TempUnschedState{
+		UntilUnix:       until.Unix(),
+		TriggeredAtUnix: now.Unix(),
+		StatusCode:      0, // 超时没有状态码
+		MatchedKeyword:  "stream_timeout",
+		RuleIndex:       -1, // 表示系统级规则
+		ErrorMessage:    "Stream data interval timeout for model: " + model,
+	}
+
+	reason := ""
+	if raw, err := json.Marshal(state); err == nil {
+		reason = string(raw)
+	}
+	if reason == "" {
+		reason = state.ErrorMessage
+	}
+
+	if err := s.accountRepo.SetTempUnschedulable(ctx, account.ID, until, reason); err != nil {
+		log.Printf("[StreamTimeout] SetTempUnschedulable failed for account %d: %v", account.ID, err)
+		return false
+	}
+
+	if s.tempUnschedCache != nil {
+		if err := s.tempUnschedCache.SetTempUnsched(ctx, account.ID, state); err != nil {
+			log.Printf("[StreamTimeout] SetTempUnsched cache failed for account %d: %v", account.ID, err)
+		}
+	}
+
+	// 重置超时计数
+	if s.timeoutCounterCache != nil {
+		if err := s.timeoutCounterCache.ResetTimeoutCount(ctx, account.ID); err != nil {
+			log.Printf("[StreamTimeout] ResetTimeoutCount failed for account %d: %v", account.ID, err)
+		}
+	}
+
+	log.Printf("[StreamTimeout] Account %d marked as temp unschedulable until %v (model: %s)", account.ID, until, model)
+	return true
+}
+
+// triggerStreamTimeoutError 触发流超时错误状态
+func (s *RateLimitService) triggerStreamTimeoutError(ctx context.Context, account *Account, model string) bool {
+	errorMsg := "Stream data interval timeout (repeated failures) for model: " + model
+
+	if err := s.accountRepo.SetError(ctx, account.ID, errorMsg); err != nil {
+		log.Printf("[StreamTimeout] SetError failed for account %d: %v", account.ID, err)
+		return false
+	}
+
+	// 重置超时计数
+	if s.timeoutCounterCache != nil {
+		if err := s.timeoutCounterCache.ResetTimeoutCount(ctx, account.ID); err != nil {
+			log.Printf("[StreamTimeout] ResetTimeoutCount failed for account %d: %v", account.ID, err)
+		}
+	}
+
+	log.Printf("[StreamTimeout] Account %d marked as error (model: %s)", account.ID, model)
+	return true
+}