fix(node-host): decode Windows exec output with active code page (openclaw#30652) thanks @Sid-Qin

Verified:
- pnpm vitest run src/node-host/invoke.sanitize-env.test.ts src/node-host/invoke-system-run.test.ts

Co-authored-by: Sid-Qin <53659198+Sid-Qin@users.noreply.github.com>
Co-authored-by: Tak Hoffman <781889+Takhoffman@users.noreply.github.com>

src/node-host/invoke.sanitize-env.test.ts

@@ -1,6 +1,6 @@
 import { describe, expect, it } from "vitest";
 import { withEnv } from "../test-utils/env.js";
-import { sanitizeEnv } from "./invoke.js";
+import { decodeCapturedOutputBuffer, parseWindowsCodePage, sanitizeEnv } from "./invoke.js";
 import { buildNodeInvokeResultParams } from "./runner.js";
 
 describe("node-host sanitizeEnv", () => {
@@ -53,6 +53,36 @@ describe("node-host sanitizeEnv", () => {
   });
 });
 
+describe("node-host output decoding", () => {
+  it("parses code pages from chcp output text", () => {
+    expect(parseWindowsCodePage("Active code page: 936")).toBe(936);
+    expect(parseWindowsCodePage("活动代码页: 65001")).toBe(65001);
+    expect(parseWindowsCodePage("no code page")).toBeNull();
+  });
+
+  it("decodes GBK output on Windows when code page is known", () => {
+    let supportsGbk = true;
+    try {
+      void new TextDecoder("gbk");
+    } catch {
+      supportsGbk = false;
+    }
+
+    const raw = Buffer.from([0xb2, 0xe2, 0xca, 0xd4, 0xa1, 0xab, 0xa3, 0xbb]);
+    const decoded = decodeCapturedOutputBuffer({
+      buffer: raw,
+      platform: "win32",
+      windowsEncoding: "gbk",
+    });
+
+    if (!supportsGbk) {
+      expect(decoded).toContain("<22>");
+      return;
+    }
+    expect(decoded).toBe("测试～；");
+  });
+});
+
 describe("buildNodeInvokeResultParams", () => {
   it("omits optional fields when null/undefined", () => {
     const params = buildNodeInvokeResultParams(