P0-6: Dify超时预算切分 native/proxy 各12s（修复proxy兜底不可达，变量已注入容器）

backend/app/services/ai_service.py

@@ -72,7 +72,8 @@ class AIService:
         """
         if self._client is None or self._client.is_closed:
             self._client = httpx.AsyncClient(
-                timeout=httpx.Timeout(self.timeout),
+                # v4.0 P0-6: proxy 路径用独立超时（12s），避免与 native 串行叠加超 wait_for(30s)
+                timeout=httpx.Timeout(settings.dify_proxy_timeout),
                 headers={
                     "Authorization": f"Bearer {self.api_key}",
                     "Content-Type": "application/json",
@@ -89,7 +90,8 @@ class AIService:
         """
         if self._native_client is None or self._native_client.is_closed:
             self._native_client = httpx.AsyncClient(
-                timeout=httpx.Timeout(self.timeout),
+                # v4.0 P0-6: native 路径用独立超时（12s），预算 12+12+开销 < wait_for(30s)
+                timeout=httpx.Timeout(settings.dify_native_timeout),
                 headers={
                     "Authorization": f"Bearer {self.native_api_key}",
                     "Content-Type": "application/json",