fix(cluster): 收敛宁波单实例数据库拓扑

将生产 CNPG 固定为宁波单实例，并显式关闭旧同步复制配置。发布流程在拓扑收敛前校验主库位置并创建 OSS 备份，应用后验证单实例、无复制连接和主库可用。同步更新生产监控、集群验收和发布脚本回归测试。

scripts/cluster/verify-cluster.sh

@@ -96,22 +96,23 @@ echo "k3s_control_plane=PASS servers=3 worker_nodes=$((expected_nodes - 3)) witn
 database_state=$(cluster_ssh "$CLUSTER_NINGBO_HOST" 'bash -s' <<'REMOTE'
 set -euo pipefail
 kubectl='k3s kubectl'
+configured_instances=$($kubectl get cluster easyai-postgres -n easyai -o jsonpath='{.spec.instances}')
 ready_instances=$($kubectl get cluster easyai-postgres -n easyai -o jsonpath='{.status.readyInstances}')
-[[ $ready_instances -eq 2 ]] || {
-  echo "postgres ready instance gate failed: ready_instances=$ready_instances expected=2" >&2
+[[ $configured_instances -eq 1 && $ready_instances -eq 1 ]] || {
+  echo "postgres single-instance gate failed: configured_instances=$configured_instances ready_instances=$ready_instances expected=1/1" >&2
   exit 1
 }
 primary=$($kubectl get cluster easyai-postgres -n easyai -o jsonpath='{.status.currentPrimary}')
 primary_node=$($kubectl get pod "$primary" -n easyai -o jsonpath='{.spec.nodeName}')
-[[ $primary_node == easyai-ningbo || $primary_node == easyai-hongkong ]] || {
+[[ $primary_node == easyai-ningbo ]] || {
   echo "postgres primary placement gate failed: primary_node=$primary_node" >&2
   exit 1
 }
 replication=$($kubectl exec -n easyai "$primary" -c postgres -- \
   psql -X -U postgres -d easyai_ai_gateway -At -c \
-  "SELECT count(*) FROM pg_stat_replication WHERE sync_state IN ('sync','quorum');")
-[[ $replication -eq 1 ]] || {
-  echo "postgres synchronous replication gate failed: synchronous_replicas=$replication expected=1" >&2
+  "SELECT count(*) FROM pg_stat_replication;")
+[[ $replication -eq 0 ]] || {
+  echo "postgres single-instance replication gate failed: replicas=$replication expected=0" >&2
   exit 1
 }
 archived_count=$($kubectl exec -n easyai "$primary" -c postgres -- \
@@ -146,17 +147,17 @@ for pod in $($kubectl get pods -n easyai -l cnpg.io/cluster=easyai-postgres \
     exit 1
   fi
 done
-[[ $readable_backup_configs -eq 2 ]] || {
-  echo "postgres projected backup config count failed: readable=$readable_backup_configs expected=2" >&2
+[[ $readable_backup_configs -eq 1 ]] || {
+  echo "postgres projected backup config count failed: readable=$readable_backup_configs expected=1" >&2
   exit 1
 }
-printf 'primary=%s archived=%s backups=%s ready=%s synchronous=%s continuous_archiving=%s backup_configs=%s\n' \
+printf 'primary=%s archived=%s backups=%s ready=%s replicas=%s continuous_archiving=%s backup_configs=%s\n' \
   "$primary" "$archived_count" "$completed_backups" "$ready_instances" \
   "$replication" "$continuous_archiving" "$readable_backup_configs"
 REMOTE
 )
 [[ $database_state == primary=easyai-postgres-* ]]
-echo "postgres_preflight=PASS $database_state synchronous_replicas=1"
+echo "postgres_preflight=PASS $database_state replicas=0 topology=ningbo-single-instance"
 
 if [[ $mode == postcutover ]]; then
   application_state=$(cluster_ssh "$CLUSTER_NINGBO_HOST" 'bash -s' <<'REMOTE'