Fix: Install Node.js via official precompiled tarball in Stage 3 to resolve setup_20.x script error

Dockerfile

@@ -18,7 +18,23 @@ WORKDIR /frontend
 COPY frontend/package.json frontend/package-lock.json* ./
 RUN npm install --legacy-peer-deps --quiet
 
-COPY frontend/ .
+# Copy only the necessary frontend files (deterministic for HF build context)
+COPY frontend/package.json frontend/package-lock.json* ./
+COPY frontend/next.config.mjs ./
+COPY frontend/tsconfig.json ./
+COPY frontend/next-env.d.ts ./
+COPY frontend/public ./public
+COPY frontend/src ./src
+COPY frontend/app ./app
+COPY frontend/pages ./pages
+
+# Verify app layout exists (better failure message in CI/HF logs)
+RUN if [ ! -d "app" ] && [ ! -d "src/app" ] && [ ! -d "pages" ]; then \
+            echo "ERROR: no 'app', 'src/app' or 'pages' directory found in frontend - Next.js requires an 'app' or 'pages' directory"; \
+            ls -la /frontend || true; \
+            ls -la /frontend/src || true; \
+            exit 1; \
+        fi
 
 # In HF, frontend calls go through the same origin via Nginx proxy
 # So NEXT_PUBLIC_API_URL is empty — rewrites handle /api/* internally
@@ -26,6 +42,9 @@ ARG NEXT_PUBLIC_API_URL=""
 ENV NEXT_PUBLIC_API_URL=$NEXT_PUBLIC_API_URL
 ENV NEXT_TELEMETRY_DISABLED=1
 
+# Increase Node heap for Next.js builds to avoid OOM in constrained builders
+ENV NODE_OPTIONS="--max-old-space-size=4096"
+
 RUN npm run build
 
 # ─── Stage 2: Python dependencies ────────────────────────────────────────────
@@ -51,8 +70,8 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
     curl \
     libpq5 \
     ca-certificates \
-    && curl -fsSL https://deb.nodesource.com/setup_20.x | bash - \
-    && apt-get install -y --no-install-recommends nodejs \
+    xz-utils \
+    && curl -fsSL https://nodejs.org/dist/v20.11.0/node-v20.11.0-linux-x64.tar.xz | tar -xJ --strip-components=1 -C /usr/local \
     && rm -rf /var/lib/apt/lists/*
 
 # ── Python packages ───────────────────────────────────────────────────────────