ci: split repo: make this repo frontend only again

frontend/Dockerfile

@@ -0,0 +1,17 @@
+FROM node:21.4-bookworm as builder
+
+WORKDIR "/src"
+
+COPY ["package.json", "yarn.lock", "./"]
+
+RUN yarn install --frozen-lockfile
+
+COPY . .
+
+RUN ./compile-less.sh
+RUN yarn build
+
+FROM nginx:latest as proxy
+
+COPY --from=builder "/src/build" "/usr/share/nginx/html"
+COPY ./nginx.conf /etc/nginx/nginx.conf