Optimize Dockerfile with multi-stage build

Also:
* Skips installing dev dependencies
* Runs as non root

Dockerfile

@@ -1,16 +1,24 @@
-FROM node:lts-alpine
+FROM node:lts-alpine AS build
 
 WORKDIR /app
 
 # Copy only package files and install deps
 # This layer will be cached as long as package*.json don't change
 COPY package*.json package-lock.json* ./
-RUN npm ci
+RUN --mount=type=cache,target=/root/.npm npm ci --omit=dev
 
 # Copy the rest of your source
 COPY . .
 
+FROM node:lts-alpine
+
 RUN apk add --no-cache openssl
 
+USER node:node
+
+WORKDIR /app
+
+COPY --from=build /app .
+
 
 EXPOSE 8080