新增测试代码规范、修复响应体断言缺失与魔法数字

- AGENTS.md 新增测试代码专项规范：常量、fixture、触发器、HTTP断言、层边界说明
- TestUpdateAllocationExpiryBaseHTTP 补全 PATCH 响应体字段断言
- 四个集成测试文件以 testIDMask 局部常量替换 0x7fffffff 魔法数字

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

internal/service/package/activation_terms_integration_test.go

@@ -1,5 +1,8 @@
 package packagepkg
 
+// testIDMask 用于将纳秒时间戳截断为合法的 uint 主键范围，仅限测试用。
+const testIDMask = testIDMask
+
 import (
 	"context"
 	"strconv"
@@ -132,7 +135,7 @@ func TestHistoricalFallbackFiresWarningAndIncrementsCounter(t *testing.T) {
 	card := createActivationTermsCard(t, tx, constants.RealNameStatusVerified)
 	pkg := createActivationTermsPackage(t, tx, constants.PackageExpiryBaseFromActivation, 21)
 	// 历史记录：四个快照字段全为空值/零值
-	unique := uint(time.Now().UnixNano() & 0x7fffffff)
+	unique := uint(time.Now().UnixNano() & testIDMask)
 	usage := &model.PackageUsage{
 		OrderID: unique, OrderNo: "UR55-HIST-" + strconv.FormatUint(uint64(unique), 10),
 		PackageID: pkg.ID, PackageName: "UR55历史测试套餐",
@@ -214,7 +217,7 @@ func createActivationTermsPackage(t *testing.T, tx *gorm.DB, expiryBase string,
 
 func createActivationTermsUsage(t *testing.T, tx *gorm.DB, packageID, cardID uint, priority int, expiryBase string, durationDays int, pendingRealname bool, createdAt time.Time) *model.PackageUsage {
 	t.Helper()
-	unique := uint(time.Now().UnixNano() & 0x7fffffff)
+	unique := uint(time.Now().UnixNano() & testIDMask)
 	usage := &model.PackageUsage{Model: gorm.Model{CreatedAt: createdAt}, OrderID: unique, OrderNo: "UR55-ACTIVATE-" + strconv.FormatUint(uint64(unique), 10), PackageID: packageID, PackageName: "UR55激活测试套餐", UsageType: constants.AssetWalletResourceTypeIotCard, IotCardID: cardID, DataLimitMB: 1, Status: constants.PackageUsageStatusPending, Priority: priority, PendingRealnameActivation: pendingRealname, Generation: 1, ExpiryBaseSnapshot: expiryBase, CalendarTypeSnapshot: constants.PackageCalendarTypeByDay, DurationDaysSnapshot: durationDays}
 	if err := tx.Omit("status", "pending_realname_activation").Create(usage).Error; err != nil {
 		t.Fatalf("创建激活测试使用记录失败：%v", err)