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/cli/src/browser/manager.ts

@@ -254,6 +254,7 @@ function whichBinary(name: string): string | undefined {
       encoding: "utf-8",
       stdio: ["pipe", "pipe", "pipe"],
       timeout: 5000,
+      windowsHide: true,
     });
     const first = output
       .split(/\r?\n/)