修正 Dockerfile 和 docker-compose.yml 配置，优化环境变量设置和健康检查命令

Dockerfile

@@ -1,5 +1,5 @@
 # Multi-stage build for OCI GenAI to OpenAI API Gateway
-FROM python:3.11-slim as builder
+FROM python:3.11-slim AS builder
 
 # 设置工作目录
 WORKDIR /app
@@ -21,7 +21,8 @@ FROM python:3.11-slim
 # 设置环境变量
 ENV PYTHONUNBUFFERED=1 \
     PYTHONDONTWRITEBYTECODE=1 \
-    PATH=/root/.local/bin:$PATH
+    PATH=/root/.local/bin:$PATH \
+    PYTHONPATH=/app/src
 
 # 设置工作目录
 WORKDIR /app