fix: 修复前端代理服务器设置清空保存后，httpx 持续报 `Unknown scheme for proxy URL (#5899)

app/utils/http.py

@@ -92,6 +92,9 @@ def _get_shared_async_transport(
     会话级状态由调用方在外层 AsyncClient(transport=...) 实例化时单独配置，
     每次调用用完即销毁，因此天然无 jar 累积串扰。
     """
+    # 规范化代理：拒绝空字符串等非法值，防止 httpx 抛出 Unknown scheme for proxy URL
+    if proxy is not None and (not proxy or not proxy.strip()):
+        proxy = None
     try:
         loop = asyncio.get_running_loop()
     except RuntimeError:
@@ -899,12 +902,17 @@ class AsyncRequestUtils:
 
         # 如果已经是字符串格式，直接返回
         if isinstance(proxies, str):
-            return proxies
+            return proxies.strip() or None
 
         # 如果是字典格式，提取http或https代理
         if isinstance(proxies, dict):
             # 优先使用https代理，如果没有则使用http代理
-            proxy_url = proxies.get("https") or proxies.get("http")
+            # 先各自 strip，避免空白字符串阻断裂合取或回退到 http 代理
+            https_proxy = proxies.get("https")
+            http_proxy = proxies.get("http")
+            https_proxy = https_proxy.strip() if isinstance(https_proxy, str) else None
+            http_proxy = http_proxy.strip() if isinstance(http_proxy, str) else None
+            proxy_url = https_proxy or http_proxy
             if proxy_url:
                 return proxy_url