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/main/kotlin/com/gzzn/omms/msgexchange/processing/BackfillService.kt

@@ -42,8 +42,6 @@ class BackfillService(
     private val log = org.slf4j.LoggerFactory.getLogger(BackfillService::class.java)
 
     companion object {
-        private val INITIAL_BACKOFF: Duration = Duration.ofSeconds(30)
-        private val MAX_BACKOFF: Duration = Duration.ofMinutes(15)
         private val TERMINAL_STATES = setOf(ProcStatus.SUCCEEDED, ProcStatus.SKIPPED, ProcStatus.DEAD)
 
         /** 放弃原因：运行时查询确认信箱行不存在（确定性结论，重试不会改变结果）。 */
@@ -51,11 +49,13 @@ class BackfillService(
 
         /** 放弃原因：暂时性故障持续到 `R` 仍未打标；停止自动重试，但保留人工恢复能力。 */
         const val ABANDON_TRANSIENT_DEADLINE = "TRANSIENT_DEADLINE"
+    }
 
-        fun backoffDelayFor(attempts: Int): Duration {
-            val shift = (attempts - 1).coerceIn(0, 20)
-            return INITIAL_BACKOFF.multipliedBy(1L shl shift).coerceAtMost(MAX_BACKOFF)
-        }
+    internal fun backoffDelayFor(attempts: Int): Duration {
+        val initial = Duration.ofMillis(props.pipeline.backfillBackoffMs)
+        val cap = Duration.ofMillis(props.pipeline.backfillBackoffCapMs)
+        val shift = (attempts - 1).coerceIn(0, 20)
+        return initial.multipliedBy(1L shl shift).coerceAtMost(cap)
     }
 
     /**