feat: Implement notification rate limiting mechanism

- Add in-memory and Redis-based notification rate limiting
- Create configurable hourly notification limits
- Implement notification limit checking for user notifications
- Add environment variables for customizing notification limits

constant/env.go

@@ -29,6 +29,9 @@ var GeminiModelMap = map[string]string{
 
 var GeminiVisionMaxImageNum = common.GetEnvOrDefault("GEMINI_VISION_MAX_IMAGE_NUM", 16)
 
+var DefaultNotifyHourlyLimit = common.GetEnvOrDefault("NOTIFY_HOURLY_LIMIT", 2)
+var NotificationLimitDurationMinute = common.GetEnvOrDefault("NOTIFICATION_LIMIT_DURATION_MINUTE", 10)
+
 func InitEnv() {
 	modelVersionMapStr := strings.TrimSpace(os.Getenv("GEMINI_MODEL_MAP"))
 	if modelVersionMapStr == "" {