feat(infra): 新增生产 Dockerfile 与部署 compose

- api-gateway/Dockerfile: 多阶段构建，golang:1.22-alpine → alpine:3.20，CGO_ENABLED=0 静态编译，非 root 运行

- teacher-portal/Dockerfile: 多阶段构建，node:20-alpine builder → runner，含 HEALTHCHECK

- docker-compose.prod.yml: 本地生产编排，3 服务，强制 DEV_MODE=false

- docker-compose.deploy.yml: 服务器部署用，镜像来自 Gitea Registry，通过 edu-shared 外部网络连接 MySQL/Redis

- deploy.env.example: 部署环境变量模板

apps/teacher-portal/Dockerfile

@@ -0,0 +1,49 @@
+# 多阶段构建：Next.js 生产镜像
+# 用法：docker build -t edu/teacher-portal:latest -f apps/teacher-portal/Dockerfile .
+
+# ============ Builder ============
+FROM node:20-alpine AS builder
+WORKDIR /app
+
+# 启用 pnpm
+RUN corepack enable && corepack prepare pnpm@9.12.0 --activate
+
+# 先拷依赖清单，利用缓存
+COPY package.json pnpm-lock.yaml* pnpm-workspace.yaml* ./
+COPY apps/teacher-portal/package.json ./apps/teacher-portal/
+# 安装依赖（含 devDependencies，构建需要）
+RUN pnpm install --filter @edu/teacher-portal... --frozen-lockfile || pnpm install --filter @edu/teacher-portal...
+
+# 拷源码
+COPY apps/teacher-portal ./apps/teacher-portal
+
+# 构建（禁用 telemetry，生产模式）
+ENV NEXT_TELEMETRY_DISABLED=1
+RUN pnpm --filter @edu/teacher-portal run build
+
+# ============ Runtime ============
+FROM node:20-alpine AS runner
+WORKDIR /app
+
+ENV NODE_ENV=production
+ENV NEXT_TELEMETRY_DISABLED=1
+ENV PORT=3000
+
+# 非 root 用户运行
+RUN addgroup -g 1001 -S nodejs && adduser -S nextjs -u 1001
+
+# 拷构建产物与必要清单
+COPY --from=builder /app/apps/teacher-portal/package.json ./package.json
+COPY --from=builder /app/apps/teacher-portal/.next ./.next
+COPY --from=builder /app/apps/teacher-portal/public ./public
+COPY --from=builder /app/node_modules ./node_modules
+COPY --from=builder /app/apps/teacher-portal/next.config.js ./next.config.js
+
+USER nextjs
+EXPOSE 3000
+
+# 健康检查
+HEALTHCHECK --interval=30s --timeout=5s --start-period=20s --retries=3 \
+  CMD wget --quiet --spider http://localhost:3000/ || exit 1
+
+CMD ["node_modules/.bin/next", "start", "-p", "3000"]