feat(delivery): 真实 Kafka 投递端口 + 闭合 G-BACKFILL-BACKOFF 配置缺口

- 新增 KafkaDeliveryPort：ProducerRegistry + 同步 Future.get() 至少一次投递，
  闭合 OPS-1 真实适配器要求与 US-07 INV-10/C-29
- 回填退避从硬编码 30s/15min 提升为 backfill-backoff-ms / backfill-backoff-cap-ms
  配置绑定，闭合 [G-BACKFILL-BACKOFF]
- 删除死依赖 micronaut-redis-lettuce（代码零引用，ACM2-28 Redis 已退出阶段 A）

src/test/kotlin/com/gzzn/omms/msgexchange/processing/BackfillServiceTest.kt

@@ -221,10 +221,11 @@ class BackfillServiceTest {
 
     @Test
     fun `backoff delay doubles per attempt and caps at fifteen minutes`() {
-        assertEquals(Duration.ofSeconds(30), BackfillService.backoffDelayFor(1))
-        assertEquals(Duration.ofMinutes(2), BackfillService.backoffDelayFor(3))
-        assertEquals(Duration.ofMinutes(15), BackfillService.backoffDelayFor(10))
-        assertEquals(Duration.ofMinutes(15), BackfillService.backoffDelayFor(50))
+        val svc = BackfillService(StubProcState(), StubInbox(), MailboxProps(), props, Clock.fixed(t0, ZoneOffset.UTC), MessageLifecycleGate())
+        assertEquals(Duration.ofSeconds(30), svc.backoffDelayFor(1))
+        assertEquals(Duration.ofMinutes(2), svc.backoffDelayFor(3))
+        assertEquals(Duration.ofMinutes(15), svc.backoffDelayFor(10))
+        assertEquals(Duration.ofMinutes(15), svc.backoffDelayFor(50))
     }
 
     @Test