feat(observability): U12 可观测底座（ACM2-10 U12/R05/N31b）

- logback：logstash 通道先加 AsyncAppender（queueSize 4096、neverBlock、discardingThreshold 0）
  ——logstash 不可达不阻塞业务线程（N31b 顺序约束：先降级再补日志）；MDC 增加 traceId/target
- 结构化日志 + MDC traceId（TraceLog.withTrace=cminmsgsId/eventId）：
  InboxService 收报 INFO；MessageProcessor SUCCEEDED/SKIPPED INFO、FAILED/解码失败 WARN、
  DEAD(MALFORMED/毒丸/EXHAUSTED) ERROR；SnapshotFlow staging/CAS WARN、快照成功 INFO；
  Dispatcher 发送 DEBUG、逐条/整批重试 WARN、DEAD(DLQ) ERROR、flushSchd 批次 INFO；
  ReplayService 重放 INFO/非法类 WARN；PipelineLifecycle 起停 INFO
- 自定义健康指示器（infra/health）：redis-flight-store / kafka-delivery——BeanProvider 可选解析，
  缺 bean（未 stub 也未实装）报 DOWN 而非启动失败；/health 聚合
- 保留：micrometer 队列深度/投递延迟 gauge 依赖版本选型（micronaut-micrometer 与平台 BOM 5.1.3
  对齐待锁），随数据层/真实 client 批次补；U13 毒丸超时告警与 DLQ 巡检入口仍属 WP2

src/main/kotlin/com/gzzn/omms/msgexchange/nextgen/PipelineLifecycle.kt

@@ -20,6 +20,7 @@ class PipelineLifecycle(
     private val pump: Pump,
     private val dispatcher: Dispatcher,
 ) {
+    private val log = org.slf4j.LoggerFactory.getLogger(PipelineLifecycle::class.java)
     private val threads = mutableListOf<Thread>()
 
     @Volatile
@@ -35,6 +36,7 @@ class PipelineLifecycle(
         started = true
         threads += spawn("msgx-pump", pump::loop)
         threads += spawn("msgx-dispatcher", dispatcher::loop)
+        log.info("pipeline loops started (pump, dispatcher)")
     }
 
     private fun spawn(name: String, body: () -> Unit): Thread =
@@ -46,5 +48,6 @@ class PipelineLifecycle(
         dispatcher.stop()
         threads.forEach { it.interrupt() }          // 解除 Thread.sleep 阻塞，加速退出
         threads.forEach { runCatching { it.join(3000) } }
+        log.info("pipeline loops stopped")
     }
 }