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/Persistence/DevelopmentSqliteMigrator.cs

@@ -58,6 +58,8 @@ public sealed class DevelopmentSqliteMigrator(
         "20260726_31_unified_message_center";
     private const string ClassroomReservationsMigration =
         "20260726_32_classroom_reservations";
+    private const string BackgroundJobOutboxMigration =
+        "20260726_33_background_job_outbox";
 
     public async Task MigrateAsync(CancellationToken cancellationToken = default)
     {
@@ -421,6 +423,19 @@ public sealed class DevelopmentSqliteMigrator(
             ClassroomReservationsMigration,
             classroomReservationsExist ? [] : ClassroomReservationStatements,
             cancellationToken);
+
+        var backgroundJobOutboxExists = await db.Database
+            .SqlQueryRaw<int>(
+                """
+                SELECT COUNT(*) AS "Value"
+                FROM sqlite_master
+                WHERE type = 'table' AND name = 'BackgroundJobOutboxMessages'
+                """)
+            .AnyAsync(value => value > 0, cancellationToken);
+        await ApplyMigrationAsync(
+            BackgroundJobOutboxMigration,
+            backgroundJobOutboxExists ? [] : BackgroundJobOutboxStatements,
+            cancellationToken);
     }
 
     private async Task ApplyMigrationAsync(
@@ -2004,4 +2019,37 @@ public sealed class DevelopmentSqliteMigrator(
         ON "ClassroomReservations" ("ReviewedByUserId");
         """
     ];
+
+    private static readonly string[] BackgroundJobOutboxStatements =
+    [
+        """
+        CREATE TABLE "BackgroundJobOutboxMessages" (
+            "Id" TEXT NOT NULL CONSTRAINT "PK_BackgroundJobOutboxMessages" PRIMARY KEY,
+            "JobKind" INTEGER NOT NULL,
+            "JobId" TEXT NOT NULL,
+            "State" INTEGER NOT NULL,
+            "PublishAttempts" INTEGER NOT NULL,
+            "ProcessingAttempts" INTEGER NOT NULL,
+            "PublishedAt" TEXT NULL,
+            "ProcessingToken" TEXT NULL,
+            "LeaseExpiresAt" TEXT NULL,
+            "CompletedAt" TEXT NULL,
+            "LastError" TEXT NULL,
+            "CreatedAt" TEXT NOT NULL,
+            "UpdatedAt" TEXT NOT NULL
+        );
+        """,
+        """
+        CREATE UNIQUE INDEX "IX_BackgroundJobOutboxMessages_JobKind_JobId"
+        ON "BackgroundJobOutboxMessages" ("JobKind", "JobId");
+        """,
+        """
+        CREATE INDEX "IX_BackgroundJobOutboxMessages_LeaseExpiresAt"
+        ON "BackgroundJobOutboxMessages" ("LeaseExpiresAt");
+        """,
+        """
+        CREATE INDEX "IX_BackgroundJobOutboxMessages_State_CreatedAt"
+        ON "BackgroundJobOutboxMessages" ("State", "CreatedAt");
+        """
+    ];
 }