feat(infra): k8s Helm Chart 演化与备份脚本测试

- 新增 edu-platform 平台级 chart（namespace/configmap/secret/ingress/hpa）
- 新增 api-gateway 服务级 chart（完整迁移自原 manifest）
- 新增 6 个业务服务 chart 桩（iam/core-edu/content/msg/data-ana/ai）
- 删除原 api-gateway-deployment.yaml（已迁移至 helm chart）
- 更新 infra/k8s/README.md 为 Helm Chart 管理说明
- 新增 backup-mysql.sh dry-run 测试脚本（17 断言）

infra/k8s/helm/msg/Chart.yaml

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+apiVersion: v2
+name: msg
+description: msg 服务级 Helm Chart
+type: application
+version: 0.1.0
+appVersion: "1.0.0"
+keywords:
+  - edu
+  - msg
+maintainers:
+  - name: edu-arch

infra/k8s/helm/msg/templates/_helpers.tpl

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+{{- define "msg.name" -}}
+{{- default .Chart.Name .Values.nameOverride | trunc 63 | trimSuffix "-" -}}
+{{- end -}}
+
+{{- define "msg.fullname" -}}
+{{- if .Values.fullnameOverride -}}
+{{- .Values.fullnameOverride | trunc 63 | trimSuffix "-" -}}
+{{- else -}}
+{{- $name := default .Chart.Name .Values.nameOverride -}}
+{{- if contains $name .Release.Name -}}
+{{- .Release.Name | trunc 63 | trimSuffix "-" -}}
+{{- else -}}
+{{- printf "%s-%s" .Release.Name $name | trunc 63 | trimSuffix "-" -}}
+{{- end -}}
+{{- end -}}
+{{- end -}}
+
+{{- define "msg.labels" -}}
+helm.sh/chart: {{ .Chart.Name }}-{{ .Chart.Version | replace "+" "_" }}
+{{ include "msg.selectorLabels" . }}
+app.kubernetes.io/managed-by: {{ .Release.Service }}
+app.kubernetes.io/part-of: edu-platform
+app.kubernetes.io/component: messaging
+{{- end -}}
+
+{{- define "msg.selectorLabels" -}}
+app.kubernetes.io/name: {{ include "msg.name" . }}
+app.kubernetes.io/instance: {{ .Release.Name }}
+{{- end -}}

infra/k8s/helm/msg/templates/deployment.yaml

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+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: {{ include "msg.name" . }}
+  namespace: {{ .Values.namespace }}
+  labels:
+    {{- include "msg.labels" . | nindent 4 }}
+spec:
+  replicas: {{ .Values.replicaCount }}
+  selector:
+    matchLabels:
+      {{- include "msg.selectorLabels" . | nindent 6 }}
+  strategy:
+    type: {{ .Values.strategy.type }}
+    rollingUpdate:
+      maxSurge: {{ .Values.strategy.maxSurge }}
+      maxUnavailable: {{ .Values.strategy.maxUnavailable }}
+  template:
+    metadata:
+      labels:
+        {{- include "msg.selectorLabels" . | nindent 8 }}
+        app.kubernetes.io/part-of: edu-platform
+        app.kubernetes.io/component: messaging
+      {{- if .Values.metrics.enabled }}
+      annotations:
+        prometheus.io/scrape: "true"
+        prometheus.io/port: {{ .Values.metrics.port | quote }}
+        prometheus.io/path: {{ .Values.metrics.path | quote }}
+      {{- end }}
+    spec:
+      containers:
+        - name: {{ include "msg.name" . }}
+          image: "{{ .Values.image.repository }}:{{ .Values.image.tag }}"
+          imagePullPolicy: {{ .Values.image.pullPolicy }}
+          ports:
+            - name: http
+              containerPort: {{ .Values.service.targetPort }}
+              protocol: TCP
+          livenessProbe:
+            httpGet:
+              path: {{ .Values.probes.liveness.path }}
+              port: http
+            initialDelaySeconds: {{ .Values.probes.liveness.initialDelaySeconds }}
+            periodSeconds: {{ .Values.probes.liveness.periodSeconds }}
+            timeoutSeconds: {{ .Values.probes.liveness.timeoutSeconds }}
+            failureThreshold: {{ .Values.probes.liveness.failureThreshold }}
+          readinessProbe:
+            httpGet:
+              path: {{ .Values.probes.readiness.path }}
+              port: http
+            initialDelaySeconds: {{ .Values.probes.readiness.initialDelaySeconds }}
+            periodSeconds: {{ .Values.probes.readiness.periodSeconds }}
+            timeoutSeconds: {{ .Values.probes.readiness.timeoutSeconds }}
+            failureThreshold: {{ .Values.probes.readiness.failureThreshold }}
+          resources:
+            {{- toYaml .Values.resources | nindent 12 }}
+          env:
+            {{- if .Values.configMap.enabled }}
+            {{- range $k, $v := .Values.configMap.data }}
+            - name: {{ $k }}
+              valueFrom:
+                configMapKeyRef:
+                  name: {{ include "msg.name" $ }}-config
+                  key: {{ $k }}
+            {{- end }}
+            {{- end }}
+            {{- range $secret := .Values.secretRefs }}
+            {{- range $key := $secret.keys }}
+            - name: {{ $key }}
+              valueFrom:
+                secretKeyRef:
+                  name: {{ $secret.name }}
+                  key: {{ $key }}
+            {{- end }}
+            {{- end }}
+          securityContext:
+            {{- toYaml .Values.securityContext | nindent 12 }}

infra/k8s/helm/msg/templates/service.yaml

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+apiVersion: v1
+kind: Service
+metadata:
+  name: {{ include "msg.name" . }}
+  namespace: {{ .Values.namespace }}
+  labels:
+    {{- include "msg.labels" . | nindent 4 }}
+spec:
+  type: {{ .Values.service.type }}
+  selector:
+    {{- include "msg.selectorLabels" . | nindent 4 }}
+  ports:
+    - name: http
+      port: {{ .Values.service.port }}
+      targetPort: http
+      protocol: TCP

infra/k8s/helm/msg/values.yaml

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+# msg 服务默认值（消息通知 - 业务领域 D5）
+
+# 副本数（生产建议 ≥ 2）
+replicaCount: 2
+
+image:
+  repository: edu/msg
+  tag: latest  # 生产请固定 tag，避免 latest
+  pullPolicy: IfNotPresent
+
+# 服务端口
+service:
+  type: ClusterIP
+  port: 3004
+  targetPort: 3004
+
+# 命名空间（默认 edu-services，由 edu-platform chart 创建）
+namespace: edu-services
+
+# 探针配置
+probes:
+  liveness:
+    path: /healthz
+    initialDelaySeconds: 15
+    periodSeconds: 20
+    timeoutSeconds: 3
+    failureThreshold: 3
+  readiness:
+    path: /readyz
+    initialDelaySeconds: 5
+    periodSeconds: 10
+    timeoutSeconds: 3
+    failureThreshold: 2
+
+# 资源配额
+resources:
+  requests:
+    cpu: 250m
+    memory: 256Mi
+  limits:
+    cpu: 1000m
+    memory: 1Gi
+
+# 滚动更新策略
+strategy:
+  type: RollingUpdate
+  maxSurge: 1
+  maxUnavailable: 0
+
+# Prometheus 指标采集
+metrics:
+  enabled: true
+  port: 3004
+  path: /metrics
+
+# 安全上下文
+securityContext:
+  runAsNonRoot: true
+  runAsUser: 1000
+  allowPrivilegeEscalation: false
+  capabilities:
+    drop: ["ALL"]
+
+# 服务级 ConfigMap（非敏感配置）
+configMap:
+  enabled: true
+  data:
+    NODE_ENV: production
+    LOG_LEVEL: info
+
+# HPA
+hpa:
+  enabled: true
+  minReplicas: 2
+  maxReplicas: 10
+  targetCPUUtilizationPercentage: 70
+  targetMemoryUtilizationPercentage: 80
+
+# 敏感配置（从 Secret 引用，Secret 由 edu-platform chart 或 ExternalSecrets 管理）
+secretRefs:
+  - name: edu-platform-secret
+    keys:
+      - MYSQL_PASSWORD
+      - JWT_SECRET
+      - REDIS_PASSWORD