参赛选手加入编号，增加导出功能

src/main/java/com/ai/da/mapper/primary/entity/Contestant.java

@@ -26,6 +26,9 @@ public class Contestant {
 
     private String email;
 
+    @TableField("contestant_number")
+    private Integer contestantNumber;
+
     @TableField("first_name")
     private String firstName;