fix(postgres): 修正跨地域 WAL 归档带宽预算

将生产 archive_timeout 从 60 秒调整为 5 分钟，避免 16 MiB WAL 段在当前宁波香港链路上持续产生高于复制吞吐的空闲流量。\n\n同步复制保持开启，双库健康时 RPO 仍为 0；单库降级时对象存储归档 RPO 保持在 5 分钟目标内。补充发布回归门禁，防止配置退回无法追平的 60 秒。\n\n验证：kubectl kustomize、bash -n、ShellCheck、manual-release-test。

deploy/kubernetes/production/database.yaml

@@ -119,7 +119,11 @@ spec:
       number: 1
       dataDurability: preferred
     parameters:
-      archive_timeout: 60s
+      # A 16 MiB WAL segment every 60 seconds requires at least 2.24 Mbit/s
+      # of continuous cross-region throughput even while the database is idle.
+      # The certified Ningbo/Hong Kong path is below that floor, so keep the
+      # object-storage RPO within five minutes without starving sync replay.
+      archive_timeout: 5min
       max_connections: "200"
       shared_buffers: 512MB
       wal_compression: "on"

docs/operations/k3s-ha-runbook.md

@@ -10,7 +10,7 @@ CloudNativePG；洛杉矶只作为 K3s server/etcd 仲裁节点，并带
 [生产同构验收模式与高媒体压力测试](production-acceptance.md)。
 
 - 健康双库：同步复制，RPO=0。
-- 单库降级：`dataDurability: preferred` 保持写入，`archive_timeout=60s`，灾难 RPO 目标不超过 5 分钟。
+- 单库降级：`dataDurability: preferred` 保持写入，`archive_timeout=5min`，灾难 RPO 目标不超过 5 分钟。生产 WAL 段为 16 MiB；禁止把该值降到 60 秒，否则仅空闲切段就要求跨地域链路持续承载至少 2.24 Mbit/s，会使同步副本在当前带宽下永久追不平。
 - 数据库故障 RTO：不超过 5 分钟。
 - 应用发布：香港验收后再滚动宁波，计划内零停机。
 - 公网入口：双 NGINX 加人工 AliDNS 切换。接入带健康检查的 GTM 前，不宣称公网入口自动高可用。

tests/release/manual-release-test.sh

@@ -290,5 +290,10 @@ grep -Fq 'gateway_tasks' "$root/deploy/manual/easyai-ai-gateway-release"
 grep -Fq 'gateway_task_attempts' "$root/deploy/manual/easyai-ai-gateway-release"
 grep -Fq 'gateway_task_events' "$root/deploy/manual/easyai-ai-gateway-release"
 grep -Fq 'production_changed=false' "$root/scripts/publish-release-images.sh"
+grep -Fq 'archive_timeout: 5min' "$root/deploy/kubernetes/production/database.yaml"
+if grep -Fq 'archive_timeout: 60s' "$root/deploy/kubernetes/production/database.yaml"; then
+  echo 'production archive timeout would exceed the certified cross-region bandwidth floor' >&2
+  exit 1
+fi
 
 echo 'manual_release_tests=PASS'