Add built-in proxy settings for Electron and Gateway (#239)

Co-authored-by: zuolingxuan <zuolingxuan@bytedance.com>

electron/utils/proxy-fetch.ts

@@ -0,0 +1,21 @@
+/**
+ * Use Electron's network stack when available so requests honor
+ * session.defaultSession.setProxy(...). Fall back to the Node global fetch
+ * for non-Electron test environments.
+ */
+
+export async function proxyAwareFetch(
+  input: string | URL,
+  init?: RequestInit
+): Promise<Response> {
+  if (process.versions.electron) {
+    try {
+      const { net } = await import('electron');
+      return await net.fetch(input, init);
+    } catch {
+      // Fall through to the global fetch.
+    }
+  }
+
+  return await fetch(input, init);
+}