feat: scaffold Micronaut+Kotlin service per ACMA-8 v4 architecture

- 4 modules (ingress/processing/delivery/reference) + codec + infra + jobs
- Flyway V2.0.0: six aux tables (PROC_STATE/MSG_EVENT/REF_DATA/REQ_TRACK/PUMP_JOB/FLIGHT_STATE)
- Lua: snapshot_replace (atomic cover+gen-diff-delete), batch_delete (3:30 sweep)
- config: env-externalized secrets, phase A/B switch, ACMA-8 param-table defaults
- logback: logstash TCP JSON + traceId MDC
- pure-logic tests: identity (I3), schd aggregation max-by-EVENT_ID (FIX #7)
- build verified: gradle compile+test green on JDK 25 (Micronaut 5.1 requires JVM 25+)

Migrated from legacy repo subdirectory per repo-strategy decision (separate repo
per service, org convention). Refs: ACMA-9, ACMA-8 v4, ACMA-6

src/main/resources/application.yml

@@ -0,0 +1,60 @@
+# =====================================================================
+# msgexchange-nextgen 配置（ACMA-8 v4）
+# 口令/端点全部环境变量外置——零入库（ACMA-8 契约冻结 + 安全基线）
+# =====================================================================
+msgx:
+  phase: A                          # A=Redis 权威（主泵单线程写，I5）；B=FLIGHT_STATE 权威+投影
+  service-name: msgexchangeapi      # 契约冻结；影子实例用 msgexchangeapi-shadow + 独立表/key前缀/topic
+  register-eureka: true             # 影子对拍期置 false 或独立服务名
+  pipeline:                         # —— ACMA-8 参数表初值（阶段 0 基线校准）——
+    poll-interval: 1s               # KEEP 现役 1s 轮询节奏
+    claim-batch: 50
+    max-attempts: 5                 # 处理/投递同值
+    backoff-ms: [1000, 2000, 4000, 8000, 16000]   # 指数退避，单次封顶 60s
+    backoff-cap-ms: 60000
+    head-deadline: 10m              # 队头滞留上界 = 最坏 HOL 时长（毒丸升级）
+  schd:
+    flush-period: 3s                # KEEP 现役推送节律
+    flush-limit: 500                # 批上限，防积压尖峰
+  identity:
+    include-day-boundary: false     # CONFIRM（矩阵 #11）：SEQN 重置作用域确认前保持关闭
+  consistency-check:                # 阶段 A 唯一主动一致性哨兵（必选）
+    on-startup: true
+    daily-sample-ratio: 0.01
+
+micronaut:
+  application:
+    name: msgexchange-nextgen
+  server:
+    port: 8080
+
+datasource:
+  url: ${MSGX_DB_URL}
+  username: ${MSGX_DB_USER}
+  password: ${MSGX_DB_PASSWORD}
+  driver-class-name: com.mysql.cj.jdbc.Driver
+
+flyway:
+  enabled: true
+  locations: classpath:db/migration
+
+redis:
+  uri: ${MSGX_REDIS_URI}            # 阶段 A 权威存储；仅主泵线程写（I5）
+
+kafka:
+  bootstrap:
+    servers: ${MSGX_KAFKA_SERVERS}
+  producers:
+    acks: all
+    enable-idempotence: true
+
+eureka:
+  client:
+    registration:
+      enabled: ${msgx.register-eureka}
+    default-zone: ${MSGX_EUREKA_URL:http://127.0.0.1:8761/eureka}
+
+# logstash TCP JSON 通道保留（字段兼容现网，ACMA-3 部署前提）——见 logback.xml
+logstash:
+  host: ${MSGX_LOGSTASH_HOST:127.0.0.1}
+  port: ${MSGX_LOGSTASH_PORT:5044}