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_tap_tempo.py

@@ -0,0 +1,49 @@
+from lintunes.tap_tempo import TapTempo
+
+
+def test_steady_taps_120_bpm():
+    tempo = TapTempo()
+    bpm = None
+    for i in range(5):
+        bpm = tempo.tap(10.0 + i * 0.5)  # 0.5s intervals = 120 bpm
+    assert bpm == 120
+
+
+def test_first_tap_gives_no_bpm():
+    tempo = TapTempo()
+    assert tempo.tap(1.0) is None
+    assert tempo.tap_count == 1
+
+
+def test_long_gap_resets_series():
+    tempo = TapTempo()
+    tempo.tap(0.0)
+    tempo.tap(0.5)
+    assert tempo.bpm() == 120
+    # 5 seconds later: new series, old taps discarded
+    assert tempo.tap(5.5) is None
+    assert tempo.tap_count == 1
+    assert tempo.tap(6.1) == 100  # 0.6s interval
+
+
+def test_window_uses_recent_taps_only():
+    tempo = TapTempo()
+    # 4 slow taps (1s = 60bpm) then 8 fast taps (0.25s = 240bpm);
+    # only the last 8 taps count, so the slow ones age out entirely
+    t = 0.0
+    for _ in range(4):
+        tempo.tap(t)
+        t += 1.0
+    for _ in range(8):
+        tempo.tap(t)
+        t += 0.25
+    assert tempo.bpm() == 240
+
+
+def test_reset():
+    tempo = TapTempo()
+    tempo.tap(0.0)
+    tempo.tap(0.5)
+    tempo.reset()
+    assert tempo.bpm() is None
+    assert tempo.tap_count == 0