Update Dockerfile.frontend via Son of Anton

Dockerfile.frontend

-FROM node:20-alpine AS base
+FROM node:20-alpine AS builder
+
 RUN apk add --no-cache libc6-compat
 
-WORKDIR /app
+WORKDIR /build
 
-# Copy everything needed
-COPY frontend/package*.json ./
+# Copy shared
+COPY shared/ ./shared/
+
+# Install frontend deps
+COPY frontend/package.json frontend/package-lock.json* ./frontend/
+WORKDIR /build/frontend
 RUN npm install --legacy-peer-deps
 
-COPY frontend/ ./
-COPY shared/ ../shared/
+# Copy frontend source
+WORKDIR /build
+COPY frontend/ ./frontend/
+
+WORKDIR /build/frontend
 
 ENV NEXT_TELEMETRY_DISABLED=1
 
+# Build needs env vars at build time for Next.js
+ARG NEXT_PUBLIC_API_URL
+ARG NEXT_PUBLIC_WS_URL
+ENV NEXT_PUBLIC_API_URL=$NEXT_PUBLIC_API_URL
+ENV NEXT_PUBLIC_WS_URL=$NEXT_PUBLIC_WS_URL
+
 RUN npm run build
 
-# Production
-FROM node:20-alpine AS runner
+# ---- Production ----
+FROM node:20-alpine
+RUN apk add --no-cache libc6-compat
 WORKDIR /app
 ENV NODE_ENV=production
 ENV NEXT_TELEMETRY_DISABLED=1
 
-COPY --from=base /app/.next/standalone ./
-COPY --from=base /app/.next/static ./.next/static
-COPY --from=base /app/public ./public
+COPY --from=builder /build/frontend/.next/standalone ./
+COPY --from=builder /build/frontend/.next/static ./.next/static
+COPY --from=builder /build/frontend/public ./public 2>/dev/null || true
 
 EXPOSE 3000
+
+HEALTHCHECK --interval=30s --timeout=5s --start-period=10s --retries=3 \
+  CMD wget -qO- http://localhost:3000/ || exit 1
+
 CMD ["node", "server.js"]
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