Import existing LinTunes project

Snapshot of the existing codebase before working through the TASKS.md
backlog. Real library data (data/) and the iTunes import fixture
(itunes-test-library/) are gitignored.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/conftest.py

@@ -0,0 +1,72 @@
+import os
+import shutil
+import subprocess
+
+import pytest
+
+# Let widget-level tests run headless; harmless for the non-GUI tests.
+os.environ.setdefault("QT_QPA_PLATFORM", "offscreen")
+
+
+@pytest.fixture(scope="session")
+def qapp():
+    """A Qt application so QObject/QTimer and real widgets work in tests.
+
+    Prefers a GUI QApplication (offscreen) so widget tests are possible;
+    QApplication is a QCoreApplication, so existing non-GUI tests are unaffected.
+    Falls back to QCoreApplication if no GUI platform is available.
+    """
+    from PyQt6.QtCore import QCoreApplication
+    inst = QCoreApplication.instance()
+    if inst is not None:
+        return inst
+    try:
+        from PyQt6.QtWidgets import QApplication
+        return QApplication([])
+    except Exception:
+        return QCoreApplication([])
+
+
+def _generate_audio(path, codec_args):
+    """Generate a 1-second sine-wave audio file with ffmpeg."""
+    if shutil.which("ffmpeg") is None:
+        pytest.skip("ffmpeg not available to generate audio fixtures")
+    result = subprocess.run(
+        ["ffmpeg", "-y", "-f", "lavfi", "-i", "sine=frequency=440:duration=1",
+         *codec_args, str(path)],
+        capture_output=True,
+    )
+    if result.returncode != 0:
+        pytest.skip(f"ffmpeg could not generate {path.suffix} fixture")
+    return path
+
+
+@pytest.fixture
+def mp3_file(tmp_path):
+    return _generate_audio(tmp_path / "test.mp3", ["-codec:a", "libmp3lame", "-b:a", "64k"])
+
+
+@pytest.fixture
+def m4a_file(tmp_path):
+    return _generate_audio(tmp_path / "test.m4a", ["-codec:a", "aac", "-b:a", "64k"])
+
+
+@pytest.fixture
+def flac_file(tmp_path):
+    return _generate_audio(tmp_path / "test.flac", ["-codec:a", "flac"])
+
+
+@pytest.fixture
+def jpeg_bytes(tmp_path):
+    """A tiny valid JPEG for artwork tests."""
+    if shutil.which("ffmpeg") is None:
+        pytest.skip("ffmpeg not available to generate image fixture")
+    path = tmp_path / "art.jpg"
+    result = subprocess.run(
+        ["ffmpeg", "-y", "-f", "lavfi", "-i", "color=red:size=8x8",
+         "-frames:v", "1", str(path)],
+        capture_output=True,
+    )
+    if result.returncode != 0:
+        pytest.skip("ffmpeg could not generate jpeg fixture")
+    return path.read_bytes()