fix: 管理员重置配额补全 monthly 字段并修复 ristretto 缓存异步问题

- 后端 handler：ResetSubscriptionQuotaRequest 新增 Monthly 字段，
  验证逻辑扩展为 daily/weekly/monthly 至少一项为 true
- 后端 service：AdminResetQuota 新增 resetMonthly 参数，
  调用 ResetMonthlyUsage；重置后追加 subCacheL1.Wait()，
  保证 ristretto Del() 的异步删除立即生效，消除重置后
  /v1/usage 返回旧用量数据的竞态窗口
- 后端测试：更新存量测试用例匹配新签名，补充
  TestAdminResetQuota_ResetMonthlyOnly /
  TestAdminResetQuota_ResetMonthlyUsageError 两个新用例
- 前端 API：resetQuota options 类型新增 monthly: boolean
- 前端视图：confirmResetQuota 改为同时重置 daily/weekly/monthly
- i18n：中英文确认提示文案更新，提及每月配额

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

backend/internal/service/subscription_service.go

@@ -31,7 +31,7 @@ var (
 	ErrSubscriptionAlreadyExists  = infraerrors.Conflict("SUBSCRIPTION_ALREADY_EXISTS", "subscription already exists for this user and group")
 	ErrSubscriptionAssignConflict = infraerrors.Conflict("SUBSCRIPTION_ASSIGN_CONFLICT", "subscription exists but request conflicts with existing assignment semantics")
 	ErrGroupNotSubscriptionType   = infraerrors.BadRequest("GROUP_NOT_SUBSCRIPTION_TYPE", "group is not a subscription type")
-	ErrInvalidInput               = infraerrors.BadRequest("INVALID_INPUT", "at least one of resetDaily or resetWeekly must be true")
+	ErrInvalidInput               = infraerrors.BadRequest("INVALID_INPUT", "at least one of resetDaily, resetWeekly, or resetMonthly must be true")
 	ErrDailyLimitExceeded         = infraerrors.TooManyRequests("DAILY_LIMIT_EXCEEDED", "daily usage limit exceeded")
 	ErrWeeklyLimitExceeded        = infraerrors.TooManyRequests("WEEKLY_LIMIT_EXCEEDED", "weekly usage limit exceeded")
 	ErrMonthlyLimitExceeded       = infraerrors.TooManyRequests("MONTHLY_LIMIT_EXCEEDED", "monthly usage limit exceeded")
@@ -696,10 +696,10 @@ func (s *SubscriptionService) CheckAndActivateWindow(ctx context.Context, sub *U
 	return s.userSubRepo.ActivateWindows(ctx, sub.ID, windowStart)
 }
 
-// AdminResetQuota manually resets the daily and/or weekly usage windows.
+// AdminResetQuota manually resets the daily, weekly, and/or monthly usage windows.
 // Uses startOfDay(now) as the new window start, matching automatic resets.
-func (s *SubscriptionService) AdminResetQuota(ctx context.Context, subscriptionID int64, resetDaily, resetWeekly bool) (*UserSubscription, error) {
-	if !resetDaily && !resetWeekly {
+func (s *SubscriptionService) AdminResetQuota(ctx context.Context, subscriptionID int64, resetDaily, resetWeekly, resetMonthly bool) (*UserSubscription, error) {
+	if !resetDaily && !resetWeekly && !resetMonthly {
 		return nil, ErrInvalidInput
 	}
 	sub, err := s.userSubRepo.GetByID(ctx, subscriptionID)
@@ -717,8 +717,18 @@ func (s *SubscriptionService) AdminResetQuota(ctx context.Context, subscriptionI
 			return nil, err
 		}
 	}
-	// Invalidate caches, same as CheckAndResetWindows
+	if resetMonthly {
+		if err := s.userSubRepo.ResetMonthlyUsage(ctx, sub.ID, windowStart); err != nil {
+			return nil, err
+		}
+	}
+	// Invalidate L1 ristretto cache. Ristretto's Del() is asynchronous by design,
+	// so call Wait() immediately after to flush pending operations and guarantee
+	// the deleted key is not returned on the very next Get() call.
 	s.InvalidateSubCache(sub.UserID, sub.GroupID)
+	if s.subCacheL1 != nil {
+		s.subCacheL1.Wait()
+	}
 	if s.billingCacheService != nil {
 		_ = s.billingCacheService.InvalidateSubscription(ctx, sub.UserID, sub.GroupID)
 	}