feat(docker): 优化 Dockerfile 支持弱网环境缓存

- 使用缓存挂载 DataX 源码，避免重复克隆提高构建效率
- 添加 NLTK 数据缓存挂载并增加失败检查机制
- 实现 PaddleOCR 模型下载缓存，支持离线重用
- 集成 spaCy 模型缓存机制，提升安装稳定性
- 优化构建流程适配弱网环境下的依赖下载

scripts/images/backend-python/Dockerfile

@@ -16,9 +16,18 @@ RUN mkdir -p /root/.m2 && \
   </mirrors>\n\
 </settings>' > /root/.m2/settings.xml
 
-RUN apt-get update && \
+# 使用缓存挂载 DataX 源码，支持弱网环境
+RUN --mount=type=cache,target=/tmp/datax-git \
+    apt-get update && \
     apt-get install -y git && \
-    git clone https://gitee.com/alibaba/DataX.git
+    if [ -d /tmp/datax-git/.git ]; then \
+        echo "Using cached DataX repository"; \
+        cd /tmp/datax-git && git pull || true; \
+    else \
+        echo "Cloning DataX repository..."; \
+        git clone https://gitee.com/alibaba/DataX.git /tmp/datax-git || exit 1; \
+    fi \
+    && cp -r /tmp/datax-git /DataX
 
 COPY runtime/datax/ DataX/
 
@@ -76,8 +85,11 @@ COPY runtime/datamate-python/pyproject.toml runtime/datamate-python/poetry.lock*
 RUN --mount=type=cache,target=$POETRY_CACHE_DIR \
     poetry install --no-root --only main
 
-# Download NLTK data
-RUN python -c "import nltk; nltk.download(['punkt_tab','averaged_perceptron_tagger_eng'], download_dir='/usr/local/nltk_data')"
+# 使用缓存挂载 NLTK 数据，支持弱网环境
+RUN --mount=type=cache,target=/usr/local/nltk_data \
+    python -c "import nltk; nltk.download(['punkt_tab','averaged_perceptron_tagger_eng'], download_dir='/usr/local/nltk_data')" || \
+    (echo "Warning: Failed to download NLTK data, checking if cache exists..." && \
+     [ -f /usr/local/nltk_data/tokenizers/punkt_tab/english/collocations.tab ] || exit 1)
 ENV NLTK_DATA=/usr/local/nltk_data
 
 # Copy the rest of the application