refactor: asset service & markdown render asset

dockerfile

@@ -21,14 +21,18 @@
 FROM node:16-alpine as builder
 WORKDIR /app
 COPY . .
+RUN apk add git
 RUN npm i -g pnpm
 RUN pnpm install
 RUN pnpm bundle
+RUN git clone https://github.com/mx-space/assets.git --depth=1
+RUN rm -rf assets/.git
 
 FROM node:16-alpine
 RUN apk add zip unzip mongodb-tools --no-cache
 
 WORKDIR /app
 COPY --from=builder /app/out .
+COPY --from=builder /app/assets ./assets
 EXPOSE 2333
 CMD node index.js --redis_host=redis --db_host=mongo