feat(acceptance): 增加生产同构媒体压力验收模式

引入动态流量门禁、隔离验收身份与协议级 Gemini/Volces 模拟器，覆盖双站点 API、Worker、PostgreSQL、River、账务、回调和媒体物化链路。

新增 P24/P28/P32 容量阶梯、Worker 强杀恢复、真实小流量 canary、CAS 放量和失败保持 validation 的生产编排；Worker 执行槽、连接池、媒体并发和双站点副本数改为环境配置。

验证：Go 全量测试、真实 PostgreSQL 迁移集成测试、迁移安全检查、OpenAPI 生成、ShellCheck、Kustomize、gofmt 和 git diff --check。

scripts/cluster/install-release-helper.sh

@@ -7,15 +7,20 @@ source "$script_dir/common.sh"
 load_cluster_env
 
 cluster_ssh "$CLUSTER_NINGBO_HOST" \
-  'install -d -m 0755 /usr/local/lib/easyai-ai-gateway-release'
+  'install -d -m 0755 /usr/local/lib/easyai-ai-gateway-release /usr/local/share/easyai-ai-gateway-release'
 cluster_scp "$cluster_root/deploy/kubernetes/easyai-ai-gateway-cluster-release" \
   "$CLUSTER_NINGBO_HOST:/usr/local/sbin/easyai-ai-gateway-cluster-release"
 cluster_scp "$cluster_root/deploy/kubernetes/easyai-ai-gateway-cluster-release.conf.example" \
-  "$CLUSTER_NINGBO_HOST:/etc/easyai-ai-gateway-cluster-release.conf"
+  "$CLUSTER_NINGBO_HOST:/usr/local/share/easyai-ai-gateway-release/easyai-ai-gateway-cluster-release.conf.example"
 cluster_scp "$cluster_root/scripts/release-manifest.mjs" \
   "$CLUSTER_NINGBO_HOST:/usr/local/lib/easyai-ai-gateway-release/release-manifest.mjs"
 cluster_ssh "$CLUSTER_NINGBO_HOST" 'bash -s' <<'REMOTE'
 set -euo pipefail
+if [[ ! -e /etc/easyai-ai-gateway-cluster-release.conf ]]; then
+  install -m 0640 \
+    /usr/local/share/easyai-ai-gateway-release/easyai-ai-gateway-cluster-release.conf.example \
+    /etc/easyai-ai-gateway-cluster-release.conf
+fi
 chmod 0750 /usr/local/sbin/easyai-ai-gateway-cluster-release
 chmod 0640 /etc/easyai-ai-gateway-cluster-release.conf
 chmod 0755 /usr/local/lib/easyai-ai-gateway-release/release-manifest.mjs