add generative evolution, cross-mod and reverb FX; expand preset bank

- 4 new params (xmod/xmix/evolve/warp) with free-running brownian evolution
- evolution: tune drift, osc2 detune sway, osc-mix crossfade, filter cutoff
  wander, resonance growl, warp drive/bias, cross-mod bloom
- per-voice unison detune spread for fat stacks
- FX engine: 3-tap ensemble chorus, filtered-feedback ping-pong delay,
  Schroeder hall reverb; new FX types 4-7 (REV HALL/ENS+REV/DLY+REV/CATHEDRAL)
- 195 presets: 40-field realignment, genre-tuned FX identities, showcase eval
- calibrate banks vs attack-inclusive peak (median 0.263); fix square-LFO
  on filter sustain collapse

Source/Params.h

@@ -13,10 +13,11 @@ enum class Id : int {
     vol,      pan,        poly,       glide, tune,
     hq,
     arpOn,    arpRate,    arpPattern, arpOct, arpGate,
-    detune1
+    detune1,
+    xmod,     xmix,       evolve,     warp
 };
 
-constexpr int num = 36;
+constexpr int num = 40;
 
 struct Desc {
     const char* id;
@@ -40,6 +41,7 @@ const char* fltTypeName (int t);
 const char* lfoShapeName (int s);
 const char* lfoTargetName (int t);
 const char* fxTypeName (int t);
+const char* xmodTypeName (int t);
 
 const char* arpRateName (int r);
 const char* arpPatternName (int p);