优化训练计划列表接口返回结构，将数据包装为对象形式，包含列表、总数、页码和限制信息。

src/training-plans/training-plans.service.ts

@@ -66,15 +66,17 @@ export class TrainingPlansService {
     });
 
     return {
-      data: rows.map(r => ({
-        id: r.id,
-        createdAt: r.createdAt,
-        startDate: r.startDate,
-        goal: r.goal,
-      })),
-      total: count,
-      page,
-      limit,
+      data: {
+        list: rows.map(r => ({
+          id: r.id,
+          createdAt: r.createdAt,
+          startDate: r.startDate,
+          goal: r.goal,
+        })),
+        total: count,
+        page,
+        limit,
+      },
     };
   }