```

feat(tournaments): 更新比赛背景字段并修复SQL语法问题

在 TournamentsMapper.xml 中新增 competition_bg 字段的支持，并修复了更新和插入语句中robot_count 字段缺少逗号的语法问题，确保 SQL语句正确拼接。
```

ruoyi-modules/ruoyi-system/src/main/resources/mapper/business/TournamentsMapper.xml

@@ -39,7 +39,8 @@ PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
             <if test="delayCardTime != null">delay_card_time = #{delayCardTime},</if>
             <if test="delayCardNum != null">delay_card_num = #{delayCardNum},</if>
             <if test="actionTime != null">action_time = #{actionTime},</if>
-            <if test="robotCount != null">robot_count = #{robotCount}</if>
+            <if test="robotCount != null">robot_count = #{robotCount},</if>
+            <if test="competitionBg != null">competition_bg = #{competitionBg}</if>
         </set>
         WHERE id = #{id}
     </update>
@@ -66,6 +67,7 @@ PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
             <if test="delayCardTime != null">delay_card_time,</if>
             <if test="delayCardNum != null">delay_card_num,</if>
             <if test="actionTime != null">action_time,</if>
+            <if test="competitionBg != null">competition_bg,</if>
         </trim>
         VALUES
         <trim prefix="(" suffix=")" suffixOverrides=",">
@@ -87,6 +89,7 @@ PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
             <if test="delayCardTime != null">#{delayCardTime},</if>
             <if test="delayCardNum != null">#{delayCardNum},</if>
             <if test="actionTime != null">#{actionTime},</if>
+            <if test="competitionBg != null">#{competitionBg},</if>
         </trim>
     </insert>