feat: professional reggaeton production engine — 7 SDD changes, 302 tests

- section-energy: track activity matrix + volume/velocity multipliers per section
- smart-chords: ChordEngine with voice leading, inversions, 4 emotion modes
- hook-melody: melody engine with hook/stabs/smooth styles, call-and-response
- mix-calibration: Calibrator module (LUFS volumes, HPF/LPF, stereo, sends, master)
- transitions-fx: FX track with risers/impacts/sweeps at section boundaries
- sidechain: MIDI CC11 bass ducking on kick hits via DrumLoopAnalyzer
- presets-pack: role-aware plugin presets (Serum/Decapitator/Omnisphere per role)

Full SDD pipeline (propose→spec→design→tasks→apply→verify) for all 7 changes.
302/302 tests passing.

.sdd/changes/smart-chords/tasks.md

@@ -0,0 +1,27 @@
+# Tasks: Smart Chord Engine
+
+## Phase 1: Foundation
+
+- [x] 1.1 Create `src/composer/chords.py` with `EMOTION_PROGRESSIONS` dict and `ChordEngine.__init__(key, seed)`
+- [x] 1.2 Implement `ChordEngine._get_degrees(emotion)` — resolve emotion → degree/quality list with `classic` fallback
+- [x] 1.3 Implement `ChordEngine._apply_inversion(voicing, inversion)` — reorder notes so target is lowest (root=0, first=1, second=2)
+
+## Phase 2: Core
+
+- [x] 2.1 Implement `ChordEngine._score_voicing(prev, cand)` — sum abs semitone diff per voice pair
+- [x] 2.2 Implement `ChordEngine._voice_leading(chords, inversion)` — greedy min-score path, cap 4 semitones/voice
+- [x] 2.3 Implement `ChordEngine.progression(bars, emotion, bpc, inversion)` — full pipeline: degrees → chords → voice leading → output
+
+## Phase 3: Integration
+
+- [x] 3.1 Modify `build_chords_track()` in `scripts/compose.py` to import + instantiate `ChordEngine`, delegate chord generation
+- [x] 3.2 Add `--emotion` and `--inversion` CLI flags to `scripts/compose.py` (default: `romantic`, `root`)
+- [x] 3.3 Wire section energy (`vm`) from existing section loop into note velocity scaling
+
+## Phase 4: Testing
+
+- [x] 4.1 Create `tests/test_chords.py` — unit test determinism: same seed → same output (R1)
+- [x] 4.2 Test voice leading: assert max semitone diff ≤ 4 across all adjacent chord pairs (R2)
+- [x] 4.3 Test inversions: assert bass note matches root/third/fifth (R3)
+- [x] 4.4 Test emotion divergence: all 4 emotions produce distinct progressions (R4)
+- [x] 4.5 Integration: `compose.py --emotion dark --output test.rpp` produces chords track using dark progression (R7)