Added .env access to frontend (+ while dockerized)

Dockerfile.frontend

@@ -0,0 +1,12 @@
+FROM node:latest as build-stage
+WORKDIR /app
+COPY ./web/admin-gui/package*.json ./
+COPY ./.env ./
+RUN npm install
+COPY ./web/admin-gui/ .
+RUN npm run build
+
+FROM nginx as production-stage
+RUN mkdir /app
+COPY --from=build-stage /app/dist /app
+COPY ./web/admin-gui/nginx.conf /etc/nginx/nginx.conf