feat(waveform): precompute and store peaks in DB for instant rendering

Store waveform peaks inline in audio_versions (JSONB columns) so WaveSurfer
can render the waveform immediately on page load without waiting for audio
decode. Adds a 100-point mini-waveform for version selector thumbnails.

Backend:
- Migration 0006: adds waveform_peaks and waveform_peaks_mini JSONB columns
- Worker generates both resolutions (500-pt full, 100-pt mini) during transcode
  and stores them directly in DB — replaces file-based waveform_url approach
- AudioVersionRead schema exposes both fields inline (no extra HTTP round-trip)
- GET /versions/{id}/waveform reads from DB; adds ?resolution=mini support

Frontend:
- audioService.initialize() accepts peaks and calls ws.load(url, Float32Array)
  so waveform renders instantly without audio decode
- useWaveform hook threads peaks option through to audioService
- PlayerPanel passes waveform_peaks from the active version to the hook
- New MiniWaveform SVG component (no WaveSurfer) renders mini peaks in the
  version selector buttons

Fix: docker-compose.dev.yml now runs alembic upgrade head before starting
the API server, so a fresh volume gets the full schema automatically.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

worker/tests/test_waveform.py

@@ -14,6 +14,12 @@ def test_extract_peaks_returns_correct_length(sine_440hz):
     assert len(peaks) == 500
 
 
+def test_extract_peaks_mini_returns_correct_length(sine_440hz):
+    audio, sr = sine_440hz
+    peaks = extract_peaks(audio, num_points=100)
+    assert len(peaks) == 100
+
+
 def test_extract_peaks_normalized_between_0_and_1(sine_440hz):
     audio, sr = sine_440hz
     peaks = extract_peaks(audio, num_points=200)
@@ -21,6 +27,13 @@ def test_extract_peaks_normalized_between_0_and_1(sine_440hz):
     assert max(peaks) == pytest.approx(1.0, abs=0.01)
 
 
+def test_extract_peaks_mini_normalized_between_0_and_1(sine_440hz):
+    audio, sr = sine_440hz
+    peaks = extract_peaks(audio, num_points=100)
+    assert all(0.0 <= p <= 1.0 for p in peaks)
+    assert max(peaks) == pytest.approx(1.0, abs=0.01)
+
+
 def test_extract_peaks_empty_audio():
     audio = np.array([], dtype=np.float32)
     peaks = extract_peaks(audio, num_points=100)
@@ -28,6 +41,14 @@ def test_extract_peaks_empty_audio():
     assert all(p == 0.0 for p in peaks)
 
 
+def test_extract_peaks_custom_num_points(sine_440hz):
+    audio, _ = sine_440hz
+    for n in [50, 100, 250, 500]:
+        peaks = extract_peaks(audio, num_points=n)
+        assert len(peaks) == n, f"Expected {n} peaks, got {len(peaks)}"
+        assert all(0.0 <= p <= 1.0 for p in peaks)
+
+
 def test_peaks_to_json_valid_structure(sine_440hz):
     audio, _ = sine_440hz
     peaks = extract_peaks(audio)
@@ -46,4 +67,5 @@ async def test_generate_waveform_file_writes_json(tmp_path, sine_440hz):
     with open(output) as f:
         data = json.load(f)
     assert data["version"] == 2
-    assert len(data["data"]) == 1000
+    # generate_waveform_file uses the default num_points=500
+    assert len(data["data"]) == 500