test: добавить скрипт сравнения onnx-asr и OpenVINO бэкендов

- Зачем:
  - Экспериментальное сравнение скорости и качества транскрипции на реальных аудиофайлах.
- Что:
  - скрипт compare_backends.py запускает транскрипцию одного файла через gigaam-v3, parakeet-v3 и OpenVINO medium.
  - выводит время, количество сегментов и превью текста для каждого.
- Проверка:
  - python scripts/compare_backends.py /path/to/audio.mp3

scripts/compare_backends.py

@@ -0,0 +1,66 @@
+"""Compare onnx-asr vs OpenVINO backends on real audio files.
+
+Usage: python scripts/compare_backends.py /path/to/audio.mp3
+"""
+import sys
+import time
+from pathlib import Path
+from local_transcriber.transcriber import load_model, _transcribe_file
+from local_transcriber.backends import get_backend
+from local_transcriber.types import Segment
+
+
+def transcribe_with_backend(file_path: Path, device: str, model_name: str,
+                            compute_type: str, language: str | None) -> tuple[float, int, str]:
+    """Run transcription and return (elapsed_sec, segment_count, transcript_text)."""
+    start = time.monotonic()
+    model_obj, actual_device, backend, model_path = load_model(
+        model_name, device, compute_type,
+        strict_device=True,
+    )
+    tfr = _transcribe_file(
+        model_obj, actual_device, backend, model_path,
+        file_path, model_name, compute_type,
+        language=language,
+    )
+    elapsed = time.monotonic() - start
+    text = " ".join(s.text for s in tfr.result.segments)
+    return elapsed, len(tfr.result.segments), text
+
+
+def main():
+    if len(sys.argv) < 2:
+        print("Usage: python scripts/compare_backends.py <audio_file>")
+        sys.exit(1)
+
+    file_path = Path(sys.argv[1])
+    if not file_path.exists():
+        print(f"File not found: {file_path}")
+        sys.exit(1)
+
+    models_to_test = [
+        ("gigaam-v3", "onnx", "int8"),
+        ("parakeet-v3", "onnx", "int8"),
+        ("medium", "openvino-cpu", "int8"),
+    ]
+
+    print(f"File: {file_path.name} ({file_path.stat().st_size / 1e6:.1f} MB)")
+    print()
+
+    for model_name, device, ct in models_to_test:
+        print(f"--- {model_name} on {device} (compute={ct}) ---")
+        try:
+            elapsed, seg_count, text = transcribe_with_backend(
+                file_path, device, model_name, ct, language="ru" if "gigaam" in model_name else None,
+            )
+            print(f"  Time: {elapsed:.1f}s")
+            print(f"  Segments: {seg_count}")
+            print(f"  Text preview: {text[:200]}...")
+            print()
+        except Exception as e:
+            print(f"  ERROR: {e}")
+            print()
+
+
+if __name__ == "__main__":
+    main()