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。

deploy/kubernetes/acceptance/kustomization.yaml

@@ -0,0 +1,4 @@
+apiVersion: kustomize.config.k8s.io/v1beta1
+kind: Kustomization
+resources:
+  - protocol-emulator.yaml

deploy/kubernetes/acceptance/protocol-emulator.yaml

@@ -0,0 +1,67 @@
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: easyai-acceptance-emulator
+  namespace: easyai
+  labels:
+    app.kubernetes.io/name: easyai-acceptance-emulator
+    app.kubernetes.io/part-of: easyai-ai-gateway
+spec:
+  replicas: 1
+  selector:
+    matchLabels:
+      app.kubernetes.io/name: easyai-acceptance-emulator
+  template:
+    metadata:
+      labels:
+        app.kubernetes.io/name: easyai-acceptance-emulator
+        app.kubernetes.io/part-of: easyai-ai-gateway
+    spec:
+      nodeSelector:
+        easyai.io/site: ningbo
+        easyai.io/workload: "true"
+      securityContext:
+        runAsNonRoot: true
+        runAsUser: 10001
+        runAsGroup: 10001
+        seccompProfile:
+          type: RuntimeDefault
+      containers:
+        - name: emulator
+          image: easyai-api
+          command: ["/app/easyai-ai-gateway-acceptance-emulator"]
+          env:
+            - name: HTTP_ADDR
+              value: ":8090"
+          ports:
+            - name: http
+              containerPort: 8090
+          readinessProbe:
+            httpGet:
+              path: /healthz
+              port: http
+          resources:
+            requests:
+              cpu: 100m
+              memory: 128Mi
+            limits:
+              cpu: "2"
+              memory: 1Gi
+          securityContext:
+            allowPrivilegeEscalation: false
+            capabilities:
+              drop: ["ALL"]
+            readOnlyRootFilesystem: true
+---
+apiVersion: v1
+kind: Service
+metadata:
+  name: easyai-acceptance-emulator
+  namespace: easyai
+spec:
+  selector:
+    app.kubernetes.io/name: easyai-acceptance-emulator
+  ports:
+    - name: http
+      port: 8090
+      targetPort: http