排课计算、课表发布、补考自动编排三类任务统一接入消息系统。

业务任务与 Outbox 消息同一事务落库，避免“数据库成功但消息没发出去”。
RabbitMQ 使用持久化消息、发布确认、手动 ACK、Quorum Queue、死信队列。
增加处理租约、心跳、异常重试、最大重试次数和幂等状态控制。
保留 InMemory 模式，开发环境无需安装 RabbitMQ。
支持多实例竞争消费，后续可以横向扩容。
新增 /health/messaging 消息系统健康检查。

src/Jiaowu.Api/Infrastructure/BackgroundJobs/BackgroundJobOptions.cs

@@ -0,0 +1,31 @@
+namespace Jiaowu.Api.Infrastructure.BackgroundJobs;
+
+public sealed class BackgroundJobOptions
+{
+    public const string SectionName = "BackgroundJobs";
+
+    public string Transport { get; set; } = "InMemory";
+    public int PollIntervalMilliseconds { get; set; } = 500;
+    public int LeaseSeconds { get; set; } = 120;
+    public ushort PrefetchCount { get; set; } = 1;
+    public string Exchange { get; set; } = "jiaowu.background-jobs";
+    public string QueuePrefix { get; set; } = "jiaowu.background-jobs";
+    public bool UseQuorumQueues { get; set; } = true;
+    public int ProcessingAttemptLimit { get; set; } = 5;
+
+    public bool UsesRabbitMq =>
+        Transport.Equals("RabbitMq", StringComparison.OrdinalIgnoreCase);
+}
+
+public sealed class RabbitMqOptions
+{
+    public const string SectionName = "RabbitMq";
+
+    public string HostName { get; set; } = "localhost";
+    public int Port { get; set; } = 5672;
+    public string UserName { get; set; } = "guest";
+    public string Password { get; set; } = "guest";
+    public string VirtualHost { get; set; } = "/";
+    public bool UseTls { get; set; }
+    public string? TlsServerName { get; set; }
+}