feat: add frontend service + dockerfile + env example

frontend/Dockerfile

@@ -0,0 +1,20 @@
+FROM node:22-alpine AS deps
+WORKDIR /app
+COPY package.json package-lock.json ./
+RUN npm ci
+
+FROM node:22-alpine AS build
+WORKDIR /app
+COPY --from=deps /app/node_modules ./node_modules
+COPY . .
+RUN npm run build
+
+FROM node:22-alpine AS runtime
+WORKDIR /app
+ENV NODE_ENV=production HOST=0.0.0.0 PORT=3000
+COPY --from=build /app/dist ./dist
+COPY --from=build /app/node_modules ./node_modules
+COPY --from=build /app/package.json ./
+USER node
+EXPOSE 3000
+CMD ["node", "./dist/server/entry.mjs"]