feat: add rate limiting and improve event handling

- Introduced rate limiting configuration in config.toml with options for enabling, requests per second (RPS), and burst capacity.
- Enhanced event handling in the OneBot11 adapter to ignore messages sent by the bot itself.
- Updated the dispatcher to register rate limit middleware based on configuration settings.
- Refactored WebSocket message handling to support flexible JSON parsing and improved event type detection.
- Removed deprecated echo plugin and associated tests to streamline the codebase.

internal/plugins/echo/echo_new.go

@@ -0,0 +1,64 @@
+package echo
+
+import (
+	"context"
+
+	"cellbot/internal/engine"
+	"cellbot/internal/protocol"
+
+	"go.uber.org/zap"
+)
+
+func init() {
+	// 在 init 函数中注册多个处理函数（类似 ZeroBot 风格）
+
+	// 处理私聊消息
+	engine.OnPrivateMessage().
+		Handle(func(ctx context.Context, event protocol.Event, botManager *protocol.BotManager, logger *zap.Logger) error {
+			// 获取消息内容
+			data := event.GetData()
+			message, ok := data["message"]
+			if !ok {
+				return nil
+			}
+
+			userID, ok := data["user_id"]
+			if !ok {
+				return nil
+			}
+
+			// 获取 bot 实例
+			selfID := event.GetSelfID()
+			bot, ok := botManager.Get(selfID)
+			if !ok {
+				bots := botManager.GetAll()
+				if len(bots) == 0 {
+					logger.Error("No bot instance available")
+					return nil
+				}
+				bot = bots[0]
+			}
+
+			// 发送回复
+			action := &protocol.BaseAction{
+				Type: protocol.ActionTypeSendPrivateMessage,
+				Params: map[string]interface{}{
+					"user_id": userID,
+					"message": message,
+				},
+			}
+
+			_, err := bot.SendAction(ctx, action)
+			if err != nil {
+				logger.Error("Failed to send reply", zap.Error(err))
+				return err
+			}
+
+			logger.Info("Echo reply sent", zap.Any("user_id", userID))
+			return nil
+		})
+
+	// 可以继续注册更多处理函数
+	// engine.OnGroupMessage().Handle(...)
+	// engine.OnCommand("help").Handle(...)
+}