fix(task-plan): purchasePackage补幂等复用并生成任务，消除active空壳

cfc-backend/src/main/java/com/etotem/cfc/controller/MarketController.java

@@ -82,7 +82,7 @@ public class MarketController {
      */
     @Operation(summary = "购买并应用任务模板")
     @PostMapping("/packages/{id}/purchase")
-    public Result<TaskPlanInstance> purchasePackage(
+    public Result<Map<String, Object>> purchasePackage(
             @PathVariable Long id,
             @RequestBody ApplyPackageDTO dto,
             @RequestAttribute("userId") Long userId) {
@@ -91,8 +91,8 @@ public class MarketController {
             return Result.noFamily("请先创建或加入家庭");
         }
         dto.setPackageId(id);
-        TaskPlanInstance instance = planService.applyPackage(dto, familyId);
-        return Result.success(instance);
+        Map<String, Object> applied = planService.applyAndActivate(dto, familyId, userId);
+        return Result.success(applied);
     }
 
     /**