提高全局连接数限制到500，优化超时配置

app.py

@@ -158,15 +158,15 @@ async def _init_global_client():
     # max_keepalive_connections: 保持活跃的连接数
     # keepalive_expiry: 连接保持时间
     limits = httpx.Limits(
-        max_keepalive_connections=60,
-        max_connections=60,  # 提高到500以支持更高并发
-        keepalive_expiry=30.0  # 30秒后释放空闲连接
+        max_keepalive_connections=500,
+        max_connections=500,  # 提高到500以支持更高并发
+        keepalive_expiry=1.0  # 30秒后释放空闲连接
     )
     # 为流式响应设置更长的超时
     timeout = httpx.Timeout(
-        connect=1.0,  # 连接超时
+        connect=2.0,  # 连接超时
         read=300.0,    # 读取超时(流式响应需要更长时间)
-        write=1.0,    # 写入超时
+        write=2.0,    # 写入超时
         pool=1.0      # 从连接池获取连接的超时时间(关键!)
     )
     GLOBAL_CLIENT = httpx.AsyncClient(mounts=mounts, timeout=timeout, limits=limits)