Add Dart API for speech enhancement GTCRN models (#1993)

dart-api-examples/speech-enhancement-gtcrn/bin/init.dart

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+../../vad/bin/init.dart

dart-api-examples/speech-enhancement-gtcrn/bin/speech_enhancement_gtcrn.dart

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+// Copyright (c)  2025  Xiaomi Corporation
+import 'dart:io';
+
+import 'package:args/args.dart';
+import 'package:sherpa_onnx/sherpa_onnx.dart' as sherpa_onnx;
+import './init.dart';
+
+void main(List<String> arguments) async {
+  await initSherpaOnnx();
+
+  final parser = ArgParser()
+    ..addOption('model', help: 'Path to gtcrn onnx model')
+    ..addOption('input-wav', help: 'Path to input.wav')
+    ..addOption('output-wav', help: 'Path to output.wav');
+
+  final res = parser.parse(arguments);
+  if (res['model'] == null ||
+      res['input-wav'] == null ||
+      res['output-wav'] == null) {
+    print(parser.usage);
+    exit(1);
+  }
+
+  final model = res['model'] as String;
+  final inputWav = res['input-wav'] as String;
+  final outputWav = res['output-wav'] as String;
+
+  final config = sherpa_onnx.OfflineSpeechDenoiserConfig(
+      model: sherpa_onnx.OfflineSpeechDenoiserModelConfig(
+    gtcrn: sherpa_onnx.OfflineSpeechDenoiserGtcrnModelConfig(model: model),
+    numThreads: 1,
+    debug: true,
+    provider: 'cpu',
+  ));
+
+  final sd = sherpa_onnx.OfflineSpeechDenoiser(config);
+
+  final waveData = sherpa_onnx.readWave(inputWav);
+
+  final denoised =
+      sd.run(samples: waveData.samples, sampleRate: waveData.sampleRate);
+
+  sd.free();
+
+  sherpa_onnx.writeWave(
+      filename: outputWav,
+      samples: denoised.samples,
+      sampleRate: denoised.sampleRate);
+
+  print('Saved to $outputWav');
+}