fix(cli): hide Windows child process consoles (#3529)

Rebase #3529 onto current main. Preserve all 16 issue-scoped Studio server, lint, and CLI child-process windowsHide options, including main's PowerShell null guards and stderr suppression in orphanCleanup.

Regression tests continue to assert windowsHide at each scoped spawn site. #3476 and #3430 remain out of scope.

Co-authored-by: heygengenesis[bot] <262951085+heygengenesis[bot]@users.noreply.github.com>
Co-authored-by: miguel.sierra <229591595+miguel-heygen@users.noreply.github.com>

packages/lint/src/hevcPreviewLint.ts

@@ -27,7 +27,7 @@ const PROBE_CONCURRENCY = 8;
 
 function execFileAsync(file: string, args: string[]): Promise<string> {
   return new Promise((resolvePromise, reject) => {
-    execFile(file, args, { timeout: PROBE_TIMEOUT_MS }, (error, stdout) => {
+    execFile(file, args, { timeout: PROBE_TIMEOUT_MS, windowsHide: true }, (error, stdout) => {
       if (error) reject(error);
       else resolvePromise(stdout.toString());
     });

packages/lint/src/hevcPreviewLint.windowsHide.test.ts

@@ -0,0 +1,32 @@
+import { describe, expect, it, vi } from "vitest";
+
+const { execFileMock } = vi.hoisted(() => ({ execFileMock: vi.fn() }));
+
+vi.mock("node:child_process", () => {
+  const mocked = { execFile: execFileMock };
+  return { ...mocked, default: mocked };
+});
+vi.mock("@hyperframes/parsers/ff-binaries", () => ({
+  findFfBinary: () => "/fake/bin/ffprobe",
+}));
+
+import { lintHevcPreviewCodec } from "./hevcPreviewLint.js";
+
+describe("HEVC preview probe options", () => {
+  it("hides the ffprobe console window", async () => {
+    execFileMock.mockImplementation(
+      (
+        _command: string,
+        _args: string[],
+        _options: unknown,
+        callback: (...args: unknown[]) => void,
+      ) => {
+        callback(null, JSON.stringify({ streams: [{ codec_name: "hevc" }] }));
+      },
+    );
+
+    await lintHevcPreviewCodec(new Map([["/tmp/clip.mp4", "clip.mp4"]]));
+
+    expect(execFileMock.mock.calls[0]?.[2]).toEqual(expect.objectContaining({ windowsHide: true }));
+  });
+});