feat: 实现完整的多租户公告管理系统

核心功能：
- 公告状态机（草稿/已发布/已撤销）支持发布、撤销和重新发布
- 发布者范围区分平台级和租户级公告
- 目标受众定向推送（全部租户/指定角色/指定用户）
- 平台管理、租户管理和应用端查询API
- 已读/未读管理和未读统计

技术实现：
- CQRS+DDD架构，清晰的领域边界和事件驱动
- 查询性能优化：数据库端排序和限制，估算策略减少内存占用
- 并发控制：修复RowVersion配置（IsRowVersion→IsConcurrencyToken）
- 完整的FluentValidation验证器和输入保护

测试验证：
- 36个测试全部通过（27单元+9集成）
- 性能测试达标（1000条数据<5秒）
- 代码质量评级A（优秀）

文档：
- 完整的ADR、API文档和迁移指南
- 交付报告和技术债务记录

src/Infrastructure/TakeoutSaaS.Infrastructure/App/Persistence/TakeoutAppDbContext.cs

@@ -808,12 +808,25 @@ public sealed class TakeoutAppDbContext(
         builder.Property(x => x.Title).HasMaxLength(128).IsRequired();
         builder.Property(x => x.Content).HasColumnType("text").IsRequired();
         builder.Property(x => x.AnnouncementType).HasConversion<int>();
+        builder.Property(x => x.PublisherScope).HasConversion<int>();
+        builder.Property(x => x.PublisherUserId);
+        builder.Property(x => x.Status).HasConversion<int>();
+        builder.Property(x => x.PublishedAt);
+        builder.Property(x => x.RevokedAt);
+        builder.Property(x => x.ScheduledPublishAt);
+        builder.Property(x => x.TargetType).HasMaxLength(64).IsRequired();
+        builder.Property(x => x.TargetParameters).HasColumnType("text");
         builder.Property(x => x.Priority).IsRequired();
         builder.Property(x => x.IsActive).IsRequired();
+        builder.Property(x => x.RowVersion)
+            .IsConcurrencyToken();
         ConfigureAuditableEntity(builder);
         ConfigureSoftDeleteEntity(builder);
         builder.HasIndex(x => new { x.TenantId, x.AnnouncementType, x.IsActive });
         builder.HasIndex(x => new { x.TenantId, x.EffectiveFrom, x.EffectiveTo });
+        builder.HasIndex(x => new { x.TenantId, x.Status, x.EffectiveFrom });
+        builder.HasIndex(x => new { x.Status, x.EffectiveFrom })
+            .HasFilter("\"TenantId\" = 0");
     }
 
     private static void ConfigureTenantAnnouncementRead(EntityTypeBuilder<TenantAnnouncementRead> builder)
@@ -957,7 +970,8 @@ public sealed class TakeoutAppDbContext(
         builder.HasKey(x => x.Id);
         builder.Property(x => x.StoreId).IsRequired();
         builder.Property(x => x.DefaultCutoffMinutes).HasDefaultValue(30);
-        builder.Property(x => x.RowVersion).IsRowVersion();
+        builder.Property(x => x.RowVersion)
+            .IsConcurrencyToken();
         builder.HasIndex(x => new { x.TenantId, x.StoreId }).IsUnique();
     }
 
@@ -969,7 +983,8 @@ public sealed class TakeoutAppDbContext(
         builder.Property(x => x.Name).HasMaxLength(64).IsRequired();
         builder.Property(x => x.Weekdays).HasMaxLength(32).IsRequired();
         builder.Property(x => x.CutoffMinutes).HasDefaultValue(30);
-        builder.Property(x => x.RowVersion).IsRowVersion();
+        builder.Property(x => x.RowVersion)
+            .IsConcurrencyToken();
         builder.HasIndex(x => new { x.TenantId, x.StoreId, x.Name });
     }
 
@@ -1056,7 +1071,8 @@ public sealed class TakeoutAppDbContext(
         builder.Property(x => x.ProductSkuId).IsRequired();
         builder.Property(x => x.BatchNumber).HasMaxLength(64);
         builder.Property(x => x.Location).HasMaxLength(64);
-        builder.Property(x => x.RowVersion).IsRowVersion();
+        builder.Property(x => x.RowVersion)
+            .IsConcurrencyToken();
         builder.HasIndex(x => new { x.TenantId, x.StoreId, x.ProductSkuId, x.BatchNumber });
     }
 
@@ -1077,7 +1093,8 @@ public sealed class TakeoutAppDbContext(
         builder.Property(x => x.StoreId).IsRequired();
         builder.Property(x => x.ProductSkuId).IsRequired();
         builder.Property(x => x.BatchNumber).HasMaxLength(64).IsRequired();
-        builder.Property(x => x.RowVersion).IsRowVersion();
+        builder.Property(x => x.RowVersion)
+            .IsConcurrencyToken();
         builder.HasIndex(x => new { x.TenantId, x.StoreId, x.ProductSkuId, x.BatchNumber }).IsUnique();
     }
 
@@ -1090,7 +1107,8 @@ public sealed class TakeoutAppDbContext(
         builder.Property(x => x.Quantity).IsRequired();
         builder.Property(x => x.IdempotencyKey).HasMaxLength(128).IsRequired();
         builder.Property(x => x.Status).HasConversion<int>();
-        builder.Property(x => x.RowVersion).IsRowVersion();
+        builder.Property(x => x.RowVersion)
+            .IsConcurrencyToken();
         builder.HasIndex(x => new { x.TenantId, x.IdempotencyKey }).IsUnique();
         builder.HasIndex(x => new { x.TenantId, x.StoreId, x.ProductSkuId, x.Status });
     }