chore: better docker build

Dockerfile

@@ -1,27 +1,37 @@
 FROM node:22.12-alpine AS base
 
-FROM base AS build
-
+# set a working dir in the base image so all stages inherit it
 WORKDIR /app
+ENV PATH=/app/node_modules/.bin:$PATH
 
+# Dependency stage: cache node_modules by only copying package files first
+FROM base AS deps
+# copy package manifests first so this layer is cached when source files change
 COPY package*.json ./
-RUN npm install
+# if you have a lockfile, copy it too (better reproducibility & cacheability)
+COPY package-lock.json ./
+# Use npm ci for deterministic installs and faster caching
+RUN npm ci --prefer-offline --no-audit --no-fund
 
+# Build stage: only run the build after deps layer is ready
+FROM deps AS build
+# copy the rest of the source
 COPY . .
 RUN npm run build:prod
 
-
-FROM base AS prod
-
+# Production stage: keep the final image small and only include what's necessary
+FROM node:22.12-alpine AS prod
 WORKDIR /app
+ENV NODE_ENV=production
 
-COPY --from=build /app/node_modules ./node_modules
+# copy production node_modules from the deps stage (they include prod + dev if needed for build)
+COPY --from=deps /app/node_modules ./node_modules
 COPY --from=build /app/dist ./dist
 COPY --from=build /app/server.js ./
 COPY --from=build /app/set_env.js ./
 COPY --from=build /app/package*.json ./
 
-
-EXPOSE 5000-7000
+# expose single well-known port instead of a wide range
+EXPOSE 5000
 
 CMD ["npm", "run", "start:prod"]