readPlatformInfo function
Returns (platform, emulator) from the platform file, or null if absent.
Implementation
({String platform, bool emulator})? readPlatformInfo() {
final file = File(platformFile);
if (!file.existsSync()) return null;
final parts = file.readAsStringSync().trim().split(' ');
if (parts.length < 2) return null;
return (platform: parts[0], emulator: parts[1] == 'true');
}