fix: 修复公告模块核心问题并完善功能

主要修复内容：
1. 修复 RowVersion 并发控制
   - 配置 EF Core RowVersion 映射为 bytea 类型
   - 添加 PostgreSQL 触发器自动生成 RowVersion
   - 在更新/发布/撤销操作中添加 RowVersion 校验
   - 移除 Application 层对 EF Core 的直接依赖

2. 修复 API 路由和校验问题
   - 添加平台公告列表路由的版本化别名
   - 租户公告接口添加 X-Tenant-Id 必填校验，返回 400
   - 生效时间校验返回 422 而非 500
   - 修复 FluentValidation 异常命名冲突

3. 实现关键词搜索功能
   - 在查询参数中添加 keyword 字段
   - 使用 PostgreSQL ILIKE 实现大小写不敏感搜索
   - 支持标题和内容字段的模糊匹配

4. 数据库迁移
   - 新增 RowVersion 触发器迁移文件
   - 回填现有公告记录的 RowVersion

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

@@ -807,10 +807,13 @@ public sealed class TakeoutAppDbContext(
         builder.Property(x => x.TenantId).IsRequired();
         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.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.Status)
+            .HasConversion<int>();
         builder.Property(x => x.PublishedAt);
         builder.Property(x => x.RevokedAt);
         builder.Property(x => x.ScheduledPublishAt);
@@ -819,7 +822,9 @@ public sealed class TakeoutAppDbContext(
         builder.Property(x => x.Priority).IsRequired();
         builder.Property(x => x.IsActive).IsRequired();
         builder.Property(x => x.RowVersion)
-            .IsConcurrencyToken();
+            .IsRowVersion()
+            .IsConcurrencyToken()
+            .HasColumnType("bytea");
         ConfigureAuditableEntity(builder);
         ConfigureSoftDeleteEntity(builder);
         builder.HasIndex(x => new { x.TenantId, x.AnnouncementType, x.IsActive });

src/Infrastructure/TakeoutSaaS.Infrastructure/App/Repositories/EfTenantAnnouncementRepository.cs

@@ -14,6 +14,7 @@ public sealed class EfTenantAnnouncementRepository(TakeoutAppDbContext context)
     /// <inheritdoc />
     public async Task<IReadOnlyList<TenantAnnouncement>> SearchAsync(
         long tenantId,
+        string? keyword,
         AnnouncementStatus? status,
         TenantAnnouncementType? type,
         bool? isActive,
@@ -29,6 +30,14 @@ public sealed class EfTenantAnnouncementRepository(TakeoutAppDbContext context)
             .IgnoreQueryFilters()
             .Where(x => tenantIds.Contains(x.TenantId));
 
+        if (!string.IsNullOrWhiteSpace(keyword))
+        {
+            var normalized = keyword.Trim();
+            query = query.Where(x =>
+                EF.Functions.ILike(x.Title, $"%{normalized}%")
+                || EF.Functions.ILike(x.Content, $"%{normalized}%"));
+        }
+
         if (status.HasValue)
         {
             query = query.Where(x => x.Status == status.Value);

src/Infrastructure/TakeoutSaaS.Infrastructure/Migrations/20251225090000_AddTenantAnnouncementRowVersionTrigger.cs

@@ -0,0 +1,50 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace TakeoutSaaS.Infrastructure.Migrations
+{
+    /// <inheritdoc />
+    public partial class AddTenantAnnouncementRowVersionTrigger : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.Sql(
+                """
+                CREATE OR REPLACE FUNCTION public.set_tenant_announcement_row_version()
+                RETURNS trigger AS $$
+                BEGIN
+                    NEW."RowVersion" = decode(md5(random()::text || clock_timestamp()::text), 'hex');
+                    RETURN NEW;
+                END;
+                $$ LANGUAGE plpgsql;
+                """);
+
+            migrationBuilder.Sql(
+                """
+                DROP TRIGGER IF EXISTS trg_tenant_announcements_row_version ON tenant_announcements;
+                CREATE TRIGGER trg_tenant_announcements_row_version
+                BEFORE INSERT OR UPDATE ON tenant_announcements
+                FOR EACH ROW EXECUTE FUNCTION public.set_tenant_announcement_row_version();
+                """);
+
+            migrationBuilder.Sql(
+                """
+                UPDATE tenant_announcements
+                SET "RowVersion" = decode(md5(random()::text || clock_timestamp()::text), 'hex')
+                WHERE "RowVersion" IS NULL OR octet_length("RowVersion") = 0;
+                """);
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.Sql(
+                """
+                DROP TRIGGER IF EXISTS trg_tenant_announcements_row_version ON tenant_announcements;
+                DROP FUNCTION IF EXISTS public.set_tenant_announcement_row_version();
+                """);
+        }
+    }
+}