Fix Dockerfile: use node:20-slim with python3 venv

Alpine's py3-numpy/scipy packages conflict with pip.
Switch to Debian-slim base with proper venv isolation.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Dockerfile

@@ -1,4 +1,4 @@
-FROM node:20-alpine AS base
+FROM node:20-slim AS base
 
 # --- Node dependencies ---
 FROM base AS deps
@@ -19,12 +19,20 @@ COPY package.json package-lock.json tsconfig.json next.config.ts postcss.config.
 ENV NEXT_TELEMETRY_DISABLED=1
 RUN npm run build
 
-# --- Final runner: Node + Python ---
-FROM node:20-alpine AS runner
+# --- Final runner ---
+FROM node:20-slim AS runner
 WORKDIR /app
 
-# Install Python + pip for the OpenEnv API
-RUN apk add --no-cache python3 py3-pip py3-numpy py3-scipy
+# Install Python for the OpenEnv API
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    python3 python3-pip python3-venv \
+    && rm -rf /var/lib/apt/lists/*
+
+# Create venv and install Python deps
+RUN python3 -m venv /opt/venv
+ENV PATH="/opt/venv/bin:$PATH"
+COPY requirements.txt ./
+RUN pip install --no-cache-dir -r requirements.txt
 
 ENV NODE_ENV=production
 ENV NEXT_TELEMETRY_DISABLED=1
@@ -39,12 +47,6 @@ COPY --from=builder /app/.next/static ./.next/static
 # Copy Python RL environment
 COPY origami_server/ ./origami_server/
 COPY training/ ./training/
-COPY requirements.txt ./
-
-# Install Python deps
-RUN pip3 install --no-cache-dir --break-system-packages -r requirements.txt
-
-# Start script: run both services
 COPY start.sh ./
 RUN chmod +x start.sh