docs: add cypress test

Dockerfile

@@ -1,5 +1,8 @@
 FROM node:lts-slim
 
+ENV NODE_ENV=production
+ENV CYPRESS_INSTALL_BINARY=0
+
 WORKDIR /app
 
 COPY / ./
@@ -9,5 +12,4 @@ RUN npm install -g pnpm
 RUN pnpm install --unsafe-perm --frozen-lockfile
 RUN pnpm run build -C packages/docs
 
-ENV NODE_ENV=production
 CMD [ "pnpm", "-C", "packages/docs", "start" ]