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/test_relocate.py

@@ -0,0 +1,47 @@
+"""LibraryManager.set_track_location: repoint a track at a moved/renamed file.
+
+It's a path repair, not a content edit — so it persists the new location and
+notifies the UI, but must not touch date_modified or write tags.
+"""
+
+from lintunes.models import Library, Track
+from lintunes.library_manager import LibraryManager
+
+
+def _manager(tmp_path):
+    track = Track(track_id=1, name="Song",
+                  location="/old/path/song.mp3",
+                  date_modified="2020-01-01T00:00:00")
+    return LibraryManager(Library(tracks={1: track}), tmp_path), track
+
+
+def test_set_track_location_repoints_and_persists(qapp, tmp_path):
+    manager, track = _manager(tmp_path)
+    updates, edits = [], []
+    manager.track_updated.connect(updates.append)
+    manager.track_fields_edited.connect(lambda tid, fields: edits.append(tid))
+
+    manager.set_track_location(1, "/new/path/from there to here.mp3")
+
+    assert track.location == "/new/path/from there to here.mp3"
+    assert manager._dirty_tracks                      # will be saved
+    assert updates == [1]                             # UI refreshes the row
+    assert edits == []                                # not a metadata edit
+    assert track.date_modified == "2020-01-01T00:00:00"  # untouched
+
+
+def test_set_track_location_noop_when_unchanged(qapp, tmp_path):
+    manager, track = _manager(tmp_path)
+    updates = []
+    manager.track_updated.connect(updates.append)
+
+    manager.set_track_location(1, track.location)
+
+    assert updates == []
+    assert not manager._dirty_tracks
+
+
+def test_set_track_location_ignores_unknown_track(qapp, tmp_path):
+    manager, _track = _manager(tmp_path)
+    manager.set_track_location(999, "/whatever.mp3")  # no such track
+    assert not manager._dirty_tracks