chore: 将后端移动到 api/ 目录，准备合并为单仓库

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

api/Dockerfile

@@ -0,0 +1,34 @@
+FROM python:3.12.2-alpine AS builder
+
+WORKDIR /app
+
+# 配置apk使用清华镜像源
+RUN sed -i 's/dl-cdn.alpinelinux.org/mirrors.tuna.tsinghua.edu.cn/g' /etc/apk/repositories
+
+# 安装构建依赖
+RUN apk add --no-cache build-base
+
+# 复制依赖文件
+COPY requirements.txt .
+
+# 使用清华镜像源安装依赖
+RUN pip config set global.index-url https://pypi.tuna.tsinghua.edu.cn/simple \
+    && pip install --no-cache-dir -r requirements.txt
+
+# 最终阶段
+FROM python:3.12.2-alpine
+
+WORKDIR /app
+
+# 从builder阶段复制Python包
+COPY --from=builder /usr/local/lib/python3.12/site-packages/ /usr/local/lib/python3.12/site-packages/
+COPY --from=builder /usr/local/bin/ /usr/local/bin/
+
+# 复制应用代码
+COPY . .
+
+RUN chmod +x /app/entrypoint.sh
+
+EXPOSE 8000
+
+ENTRYPOINT ["/app/entrypoint.sh"]