instrument: the filter's velocity depth knob returns and multiplies the bipolar curve; the pre-v12 lift is a pure domain re-tag

src/core/instrument/ui/deck_groups.cpp

@@ -48,6 +48,7 @@ std::vector<DeckGroupDesc> sampleDeckGroups(PlayMode playMode) {
                           id(DeckParam::kFilterQ),
                           id(DeckParam::kFilterDrive),
                           id(DeckParam::kFilterModAmt),
+                          id(DeckParam::kFilterVel),
                           id(DeckParam::kFilterKeyTrack)};
         filter.rowToggle = {id(DeckParam::kFilterLaw), 44};
         out.push_back(std::move(filter));
@@ -164,6 +165,7 @@ bool isLiveDeckParam(DeckParam id) {
         case DeckParam::kFilterQ:
         case DeckParam::kFilterDrive:
         case DeckParam::kFilterModAmt:
+        case DeckParam::kFilterVel:
         case DeckParam::kFilterKeyTrack:
         case DeckParam::kFilterEnvAttack:
         case DeckParam::kFilterEnvHold:
@@ -250,6 +252,7 @@ bool deckKnobInert(DeckParam id, bool pitchEnvEnabled, bool filterEnabled) {
         case DeckParam::kFilterQ:
         case DeckParam::kFilterDrive:
         case DeckParam::kFilterModAmt:
+        case DeckParam::kFilterVel:
         case DeckParam::kFilterKeyTrack:
         // The filter's velocity curve sits in the VELOCITY group but is a filter parameter:
         // it goes inert with every other one, so no surface can reach a param the knobs can't.

src/core/instrument/ui/deck_groups.h

@@ -40,6 +40,7 @@ enum class DeckParam {
     kFilterQ,        // resonance
     kFilterDrive,    // in-loop drive depth
     kFilterModAmt,   // filter envelope -> cutoff, +/-100%
+    kFilterVel,      // velocity curve -> cutoff depth, +/-100%
     kFilterKeyTrack, // note -> cutoff, 0..200%
     kFilterLaw,      // morph law row toggle: HP-BP-LP | HP-notch-LP
     kFilterEnvAttack,   // filter AHDSR (Gate)
@@ -128,7 +129,9 @@ DeckParam curveParamFor(DeckParam knob);
 //     the decoded PCM;
 //   - kKeyTrack and the three velocity-curve cells feed values a voice latches at note-on by
 //     design (the pitch ratio and the curve results), so live delivery would retune or re-gain
-//     a note already struck;
+//     a note already struck. kFilterVel is NOT one of them: it is the DEPTH over the filter
+//     curve's latched result, the exact shape kFilterKeyTrack already has over the latched note
+//     number, and it glides through the same base-cutoff ramp;
 //   - kTrigLength resolves playEnd_, a fact about the note, not a setting of it;
 //   - the overlay radios select what the editor DRAWS and reach no parameter at all.
 // Both amp shapes are live: the Trigger fade pair that used to reload folded into the AHD and