initialize static method
Initializes the native optimizer by locating available tools.
Must be called before using toWebp or optimizePng.
Implementation
static Future<void> initialize() async {
if (_initialized) return;
_cwebpPath = await _resolveTool('cwebp', ['-version']);
_pngquantPath = await _resolveTool('pngquant', ['--version']);
_initialized = true;
}