Re-consider or documentpolygen-metro-config being an ESM target

[kraenhansen]

The "require(esm)" feature of Node.js being enabled by default is fairly recent and Metro doesn't support ESM configs yet.

Metro loads the "polygen-metro-config" from a CJS context (at least in the Example app). Either these packages shouldn't be "type": "module" (polygen-metro-config and polygen-core-build) or there should be a loud note about running the latest versions of Node in the README or some FAQ. Another alternative would be to add a .cjs wrapper of your ESM code and throwing a nice error urging users to upgrade.