ci: optimize docker build for space - use build cache and aggressive cleanup

Author: camille-004

Dockerfile.ci

@@ -9,33 +9,39 @@ ARG PYTHON_VERSION=3.10
 ENV PYTHON_VERSION=${PYTHON_VERSION}
 ENV DEBIAN_FRONTEND=noninteractive
 
-RUN apt-get update && apt-get install -y --no-install-recommends \
-    git \
-    wget \
-    cmake \
-    build-essential \
-    software-properties-common \
-    && rm -rf /var/lib/apt/lists/*
-RUN add-apt-repository -y ppa:deadsnakes/ppa && \
+# Install system dependencies and Python versions in one layer with aggressive cleanup
+RUN --mount=type=cache,target=/var/cache/apt,sharing=locked \
+    --mount=type=cache,target=/var/lib/apt,sharing=locked \
     apt-get update && \
-    apt-get install -y \
-    python3.10 python3.10-venv python3.10-dev \
-    python3.11 python3.11-venv python3.11-dev \
-    python3.12 python3.12-venv python3.12-dev \
-    python3.13 python3.13-venv python3.13-dev \
-    python3-pip \
-    && rm -rf /var/lib/apt/lists/*
+    apt-get install -y --no-install-recommends \
+        git wget cmake build-essential 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 \
+        python3.11 python3.11-venv python3.11-dev \
+        python3.12 python3.12-venv python3.12-dev \
+        python3.13 python3.13-venv python3.13-dev \
+        python3-pip && \
+    rm -rf /var/lib/apt/lists/* /var/cache/apt/* /tmp/*
 
 COPY test/requirements.txt /tmp/requirements-test.txt
 COPY docs/requirements.txt /tmp/requirements-docs.txt
 
 # Set environment variable to allow pip installs in managed environment
 ENV PIP_BREAK_SYSTEM_PACKAGES=1
 
-RUN pip install --no-cache-dir setuptools wheel build
-RUN pip install --no-cache-dir \
-    -r /tmp/requirements-test.txt \
-    -r /tmp/requirements-docs.txt
+# Install all dependencies in one layer with aggressive cleanup to save space
+RUN --mount=type=cache,target=/root/.cache/pip \
+    pip install --no-cache-dir setuptools wheel build && \
+    pip install --no-cache-dir \
+        -r /tmp/requirements-test.txt \
+        -r /tmp/requirements-docs.txt && \
+    rm -rf /tmp/* && \
+    find /usr -name "*.pyc" -delete && \
+    find /usr -name "__pycache__" -type d -exec rm -rf {} + 2>/dev/null || true && \
+    apt-get clean && \
+    rm -rf /var/lib/apt/lists/* /var/cache/apt/*
 ENV CUDA_HOME="/usr/local/cuda"
 ENV PATH="$PATH:/usr/local/cuda/bin"
 ENV LD_LIBRARY_PATH="/usr/local/cuda/lib64:${LD_LIBRARY_PATH}"