fix: run macOS test-app scaffolding via pnpm dlx (avoid npm devEngines error)

The test-macos job failed at `init-macos-test-app`: it scaffolds the app with
`npx @react-native-community/cli init` run from the workspace root, whose
package.json now declares `devEngines.packageManager: pnpm`. npm 11 refuses to
run (EBADDEVENGINES) because it isn't pnpm.

Switch that single root-level invocation to `pnpm dlx` — pnpm doesn't enforce
devEngines.packageManager (and satisfies it anyway). The remaining steps
(`npm install`, `npx react-native-macos-init`) run inside the scaffolded
standalone app directory, which isn't linked to the root as a workspace, so
they keep using npm/npx unaffected. Keeps the devEngines guardrail intact.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DnwodAoNbqPec77191HVXn

Author: claude

scripts/init-macos-test-app.ts

@@ -29,7 +29,13 @@ async function deletePreviousApp() {
 
 async function initializeReactNativeTemplate() {
   console.log("Initializing community template");
-  exec("npx", [
+  // Use `pnpm dlx` rather than `npx` here: this runs from the workspace root,
+  // whose package.json declares `devEngines.packageManager: pnpm`, and npm 11
+  // refuses (EBADDEVENGINES) to run when invoked as npm/npx. The subsequent
+  // steps run inside the scaffolded, standalone macos-test-app directory (no
+  // `workspaces` field links it to the root) and can keep using npm/npx.
+  exec("pnpm", [
+    "dlx",
     "@react-native-community/cli",
     "init",
     "MacOSTestApp",