fix: CommissionSummaryDTO 增加 totalEarnings 字段，修复 wealth 页累计收益显示为0

wealth/index.vue 读取 commissionRes.data.totalEarnings，但 DTO 只有
totalCommission，导致 undefined || 0 显示为 0。新增同值字段保持兼容。

cfc-backend/src/main/java/com/etotem/cfc/dto/CommissionSummaryDTO.java

@@ -6,6 +6,8 @@ import lombok.Data;
 @Data
 public class CommissionSummaryDTO {
     private Integer totalCommission;
+    /** 累计收益，与 totalCommission 同值，供前端 wealth 页面使用 */
+    private Integer totalEarnings;
     private Integer settledAmount;
     private Integer pendingAmount;
     private Integer withdrawnAmount;

cfc-backend/src/main/java/com/etotem/cfc/service/CommissionService.java

@@ -439,6 +439,7 @@ public class CommissionService {
                 .mapToInt(r -> r.getCommissionAmount() != null ? r.getCommissionAmount() : 0)
                 .sum();
         dto.setTotalCommission(totalCommission);
+        dto.setTotalEarnings(totalCommission);
 
         // 已结算（settled）
         LambdaQueryWrapper<CommissionRecord> settledWrapper = new LambdaQueryWrapper<CommissionRecord>()