chore: add documentation comments and stylecop rules

src/Application/TakeoutSaaS.Application/App/Tenants/Handlers/GetTenantAnnouncementQueryHandler.cs

@@ -17,12 +17,14 @@ public sealed class GetTenantAnnouncementQueryHandler(
 {
     public async Task<TenantAnnouncementDto?> Handle(GetTenantAnnouncementQuery request, CancellationToken cancellationToken)
     {
+        // 1. 查询公告主体
         var announcement = await announcementRepository.FindByIdAsync(request.TenantId, request.AnnouncementId, cancellationToken);
         if (announcement == null)
         {
             return null;
         }
 
+        // 2. 优先查用户级已读
         var userId = currentUserAccessor?.UserId ?? 0;
         var reads = await readRepository.GetByAnnouncementAsync(
             request.TenantId,
@@ -37,6 +39,7 @@ public sealed class GetTenantAnnouncementQueryHandler(
             reads = tenantReads;
         }
 
+        // 3. 返回 DTO 并附带已读状态
         var readRecord = reads.FirstOrDefault();
         return announcement.ToDto(readRecord != null, readRecord?.ReadAt);
     }