fix(botp): ConvertRule 补分单字段名称并实现 Serializable

- 分单策略的配套字段只有 groupByField，缺少用于展示的 groupByFieldName，
  前端选中分组字段后无法回显名称，补上该字段（仅展示用途，不参与分单计算，
  执行侧仍按 field id 取分组依据）
- 实体实现 Serializable，与 ReverseWritingRules 等规则实体保持一致

common/common-botp/src/main/java/apelet/common/botp/model/ConvertRule.java

@@ -12,6 +12,7 @@ import com.baomidou.mybatisplus.annotation.*;
 import io.swagger.v3.oas.annotations.media.Schema;
 import lombok.Data;
 
+import java.io.Serializable;
 import java.util.List;
 import java.util.Map;
 
@@ -22,7 +23,7 @@ import java.util.Map;
 @Data
 @Schema( description = "转换规则存值主表")
 @TableName("convert_rule")
-public class ConvertRule extends BaseModel {
+public class ConvertRule extends BaseModel implements Serializable {
 
     private static final long serialVersionUID = 1L;
 
@@ -167,6 +168,10 @@ public class ConvertRule extends BaseModel {
     @Schema(description = "分单字段")
     private String groupByField;
 
+    @Excel(name = "分单字段名称", width = 15)
+    @Schema(description = "分单字段名称")
+    private String groupByFieldName;
+
     @Excel(name = "规则启用条件", width = 15)
     @Schema(description = "规则启用条件，,留空 = 始终启用")
     private String enableConditionJson;