create static method
Creates a builder backed by the pure-Dart WASM bridge (ScWasmRunBridge),
loading sc.wasm from the package bundle. No native library required.
This is the default and matches the long-standing behaviour; existing callers keep running unchanged.
Implementation
static Future<ScTransactionBuilder> create() async {
final wasmBytes = await _loadPackageWasm();
return ScTransactionBuilder(wasmBridge: ScWasmRunBridge(wasmBytes));
}