feat: optimize Docker image with multi-stage build

- Use multi-stage build to exclude build dependencies from final image
- Separate builder stage using devel image from runtime stage using smaller base image
- Clean venv: remove __pycache__, .pyc files, and test directories
- Remove embedded model files (243MB) from app/model/ - mount at runtime instead
- Expected size reduction: 18.9GB → 2-3GB (80-90% reduction)

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

Dockerfile

@@ -1,7 +1,55 @@
-# DocProcesser Dockerfile
+# DocProcesser Dockerfile - Multi-stage optimized build
 # Optimized for RTX 5080 GPU deployment
 
-# Use NVIDIA CUDA base image with Python 3.10
+# =============================================================================
+# STAGE 1: Builder - Install dependencies
+# =============================================================================
+FROM nvidia/cuda:12.9.0-devel-ubuntu24.04 AS builder
+
+# Install build dependencies and Python 3.10
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    software-properties-common \
+    && add-apt-repository -y ppa:deadsnakes/ppa \
+    && apt-get update && apt-get install -y --no-install-recommends \
+    python3.10 \
+    python3.10-venv \
+    python3.10-dev \
+    python3.10-distutils \
+    build-essential \
+    curl \
+    && rm -rf /var/lib/apt/lists/*
+
+# Setup Python
+RUN ln -sf /usr/bin/python3.10 /usr/bin/python && \
+    ln -sf /usr/bin/python3.10 /usr/bin/python3 && \
+    curl -sS https://bootstrap.pypa.io/get-pip.py | python3.10
+
+# Install uv
+RUN python3.10 -m pip install uv -i https://pypi.tuna.tsinghua.edu.cn/simple
+
+WORKDIR /build
+
+# Copy dependency files
+COPY pyproject.toml ./
+COPY wheels/ ./wheels/
+
+# Create virtual environment with dependencies
+RUN uv venv /build/venv --python python3.10 && \
+    . /build/venv/bin/activate && \
+    uv pip install -i https://pypi.tuna.tsinghua.edu.cn/simple -e . && \
+    rm -rf ./wheels
+
+# Clean up venv - remove unnecessary files
+RUN find /build/venv -type d -name "__pycache__" -exec rm -rf {} + 2>/dev/null || true && \
+    find /build/venv -type d -name "*.dist-info/tests" -exec rm -rf {} + 2>/dev/null || true && \
+    find /build/venv -type f -name "*.pyc" -delete && \
+    find /build/venv -type f -name "*.pyo" -delete && \
+    find /build/venv -type d -name "tests" -exec rm -rf {} + 2>/dev/null || true && \
+    find /build/venv -type d -name "test" -exec rm -rf {} + 2>/dev/null || true
+
+# =============================================================================
+# STAGE 2: Runtime - Minimal final image
+# =============================================================================
 FROM nvidia/cuda:12.9.0-runtime-ubuntu24.04
 
 # Set environment variables
@@ -15,20 +63,15 @@ ENV PYTHONUNBUFFERED=1 \
     # Application config (override defaults for container)
     # Use 127.0.0.1 for --network host mode, or override with -e for bridge mode
     PP_DOCLAYOUT_MODEL_DIR=/root/.cache/modelscope/hub/models/PaddlePaddle/PP-DocLayoutV2 \
-    PADDLEOCR_VL_URL=http://127.0.0.1:8001/v1
+    PADDLEOCR_VL_URL=http://127.0.0.1:8001/v1 \
+    PATH="/app/.venv/bin:$PATH" \
+    VIRTUAL_ENV="/app/.venv"
 
-# Set working directory
 WORKDIR /app
 
-# Install system dependencies and Python 3.10 from deadsnakes PPA
+# Install runtime-only system dependencies (NO build tools)
 RUN apt-get update && apt-get install -y --no-install-recommends \
-    software-properties-common \
-    && add-apt-repository -y ppa:deadsnakes/ppa \
-    && apt-get update && apt-get install -y --no-install-recommends \
     python3.10 \
-    python3.10-venv \
-    python3.10-dev \
-    python3.10-distutils \
     libgl1 \
     libglib2.0-0 \
     libsm6 \
@@ -37,34 +80,24 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
     libgomp1 \
     curl \
     pandoc \
-    && rm -rf /var/lib/apt/lists/* \
+    && rm -rf /var/lib/apt/lists/*
-    && ln -sf /usr/bin/python3.10 /usr/bin/python \
-    && ln -sf /usr/bin/python3.10 /usr/bin/python3 \
-    && curl -sS https://bootstrap.pypa.io/get-pip.py | python3.10
 
-# Install uv via pip (more reliable than install script)
+# Setup Python symlinks
-RUN python3.10 -m pip install uv -i https://pypi.tuna.tsinghua.edu.cn/simple
+RUN ln -sf /usr/bin/python3.10 /usr/bin/python && \
-ENV PATH="/app/.venv/bin:$PATH"
+    ln -sf /usr/bin/python3.10 /usr/bin/python3
-ENV VIRTUAL_ENV="/app/.venv"
 
-# Copy dependency files first for better caching
+# Copy pre-built venv from builder stage
-COPY pyproject.toml ./
+COPY --from=builder /build/venv /app/.venv
-COPY wheels/ ./wheels/
 
-# Create virtual environment and install dependencies
+# Copy application code (excluding model files if they're in the repo)
-RUN uv venv /app/.venv --python python3.10 \
-    && uv pip install -i https://pypi.tuna.tsinghua.edu.cn/simple -e . \
-    && rm -rf ./wheels
-
-# Copy application code
 COPY app/ ./app/
 
 # Create model cache directories (mount from host at runtime)
+# NOTE: Remove model files from app/model to keep image lean
 RUN mkdir -p /root/.cache/modelscope \
     /root/.cache/huggingface \
-    /root/.paddlex \
+    /root/.paddlex && \
-    /app/app/model/DocLayout \
+    rm -rf /app/app/model/*
-    /app/app/model/PP-DocLayout
 
 # Declare volumes for model cache (mount at runtime to avoid re-downloading)
 VOLUME ["/root/.cache/modelscope", "/root/.cache/huggingface", "/root/.paddlex"]