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/mix-calibration/spec.md

@@ -0,0 +1,106 @@
+# mix-calibration Specification
+
+## Purpose
+
+Post-processing calibrator that applies role-aware volume, EQ, stereo width, sends, and mastering chain to a `SongDefinition` before `.rpp` generation.
+
+## Requirements
+
+### Requirement: Calibrator Post-Processing
+
+The system MUST provide a `Calibrator.apply(song: SongDefinition) -> SongDefinition` method that mutates and returns the song with calibrated mix settings. Calibration MUST run as a distinct step between track construction and `RPPBuilder.build()`.
+
+#### Scenario: Happy path — full calibration
+
+- GIVEN a complete `SongDefinition` with 7 tracks (Drumloop, Perc, 808 Bass, Chords, Lead, Clap, Pad) and 2 return tracks
+- WHEN `Calibrator.apply(song)` is called
+- THEN `song.tracks[].volume` matches role-based LUFS targets
+- AND each non-return track has a ReaEQ plugin prepended to its `plugins` list
+- AND `song.tracks[].pan` follows stereo-width rules
+- AND `song.tracks[].send_level` contains calibrated reverb/delay values
+- AND `song.master_plugins` contains Ozone 12 Equalizer, Dynamics, Maximizer
+
+### Requirement: Role-Based Volumes
+
+The system SHALL set track volumes from a preset table keyed by track role (name → role mapping). Volumes MUST be in the REAPER-compatible 0.0–1.0 range.
+
+| Role | Volume | Target |
+|------|--------|--------|
+| drumloop | 0.85 | kick prominence |
+| bass | 0.72 | sub-presence |
+| chords | 0.78 | harmonic support |
+| lead | 0.78 | melody clarity |
+| clap | 0.75 | transient punch |
+| pad | 0.68 | ambient depth |
+| perc | 0.72 | groove feel |
+
+#### Scenario: Unknown track role
+
+- GIVEN a track with name not matching any preset role
+- WHEN calibrated
+- THEN the track's volume and pan remain unchanged (preserved as-is)
+
+### Requirement: HPF/LPF EQ per Role
+
+The system SHALL prepend a ReaEQ `PluginDef` to each non-return track's `plugins` list with appropriate HPF or LPF parameters. Bass tracks (808 Bass) SHALL receive LPF. All other tracks SHALL receive HPF.
+
+#### Scenario: HPF on lead/chords/pad tracks
+
+- GIVEN a track named "Chords", "Lead", "Pad", "Clap", "Perc", or "Drumloop"
+- WHEN calibrated
+- THEN a ReaEQ plugin is inserted at `plugins[0]` with param `0=1` (band enabled), `1=1` (HPF type), `2=200.0` (frequency for melodic) or `2=60.0` (drums)
+
+#### Scenario: LPF on bass track
+
+- GIVEN a track named "808 Bass"
+- WHEN calibrated
+- THEN a ReaEQ plugin is inserted at `plugins[0]` with param `0=1`, `1=0` (LPF type), `2=300.0` (frequency)
+
+#### Scenario: Return tracks excluded
+
+- GIVEN tracks named "Reverb" or "Delay"
+- WHEN calibrated
+- THEN no ReaEQ plugin is added (return tracks are skipped)
+
+### Requirement: Stereo Width per Role
+
+The system SHALL set track pan values to role-specific defaults.
+
+| Role | Pan | Rationale |
+|------|-----|-----------|
+| drumloop | 0.0 | mono center |
+| bass | 0.0 | mono sub |
+| chords | +0.5 | wide right |
+| lead | +0.3 | right-leaning |
+| clap | -0.15 | off-center left |
+| pad | -0.5 | wide left |
+| perc | +0.12 | slight right |
+
+### Requirement: Send Calibration
+
+The system SHALL set `send_level` dict entries for reverb (index=return_track_count) and delay (index=return_track_count+1) on each non-return track.
+
+| Role | Reverb | Delay |
+|------|--------|-------|
+| drumloop | 0.10 | 0.00 |
+| bass | 0.05 | 0.02 |
+| chords | 0.30 | 0.10 |
+| lead | 0.25 | 0.15 |
+| clap | 0.10 | 0.00 |
+| pad | 0.40 | 0.20 |
+| perc | 0.10 | 0.00 |
+
+### Requirement: Master Chain Upgrade
+
+The system SHALL replace `master_plugins` with `["Ozone_12_Equalizer","Ozone_12_Dynamics","Ozone_12_Maximizer"]`. If registry lookup for any Ozone plugin fails, the system MUST fall back to `["Pro-Q_3","Pro-C_2","Pro-L_2"]`.
+
+### Requirement: Calibration Toggle
+
+The system SHALL support a `--no-calibrate` CLI flag. When passed, `Calibrator.apply()` MUST NOT be called. When omitted (default), calibration MUST run. `SongMeta` MAY include an optional `calibrate: bool` field defaulting to `True`.
+
+#### Scenario: --no-calibrate preserves existing behavior
+
+- GIVEN `compose.py --no-calibrate -o out.rpp`
+- WHEN the song is built
+- THEN `Calibrator.apply()` is never invoked
+- AND the generated `.rpp` matches the pre-calibration baseline