build(docker): add Docker build and deployment infrastructure

- Add multi-stage Dockerfile with pnpm install and Nginx serving
- Add nginx.conf with gzip and SPA fallback
- Add docker-build.sh script for building and pushing images
- Add .dockerignore for build context optimization
- Remove unused pnpm-workspace.yaml

Dockerfile

@@ -0,0 +1,15 @@
+# 第一阶段：构建前端
+FROM node:22-alpine AS builder
+WORKDIR /app
+RUN corepack enable
+COPY package.json pnpm-lock.yaml ./
+RUN pnpm install --frozen-lockfile --ignore-scripts && \
+    pnpm rebuild esbuild
+COPY . .
+RUN pnpm build
+
+# 第二阶段：Nginx 服务
+FROM nginx:alpine
+COPY --from=builder /app/dist /usr/share/nginx/html
+COPY nginx.conf /etc/nginx/conf.d/default.conf
+EXPOSE 80