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

tests/test_live_delivery.cpp

@@ -63,6 +63,10 @@ static SampleData filteredSine() {
     s.play.filter.settings.cutoffNorm = 0.8f;
     s.play.filter.settings.resonanceNorm = 0.9f;
     s.play.filter.settings.morphNorm = 1.0f;
+    // A drawn velocity curve, so the velocity-DEPTH knob has something to scale. It costs
+    // every other case nothing: the depth is 0 until a case moves it, so the product is 0.
+    s.play.filter.velocityCurve = VelocityCurve::fromPoints(
+        {{0.0, 0.0}, {127.0, -1.0}}, instrument::engine::CurveDomain::Bipolar);
     return s;
 }
 
@@ -601,6 +605,10 @@ static void testEveryLiveFilterControlMovesTheSoundingNote() {
         {"morph",  [](LiveValues& v) { v.filterSettings.morphNorm = 0.0f; }},
         {"drive",  [](LiveValues& v) { v.filterSettings.driveNorm = 1.0f; }},
         {"mod",    [](LiveValues& v) { v.filterModAmount = 1.0; }},
+        // The velocity DEPTH is live even though the velocity itself is latched: the depth is
+        // a control over the note's latched curve value, the same shape key-track has over the
+        // note's latched number (deck_groups.h).
+        {"velamount", [](LiveValues& v) { v.filterVelAmount = 1.0; }},
         {"keytrack", [](LiveValues& v) { v.filterKeyTrack = 2.0; }},
     };
 
@@ -644,7 +652,7 @@ static void testEveryLiveFilterControlMovesTheSoundingNote() {
         // The window is a FRACTION OF THE GLIDE, not a frame count: kLiveRampSeconds is the
         // full travel time, so at 1/240 of it a working glide has barely started when the
         // window closes. kGlideMargin then puts the bound at the geometric middle of the two
-        // MEASURED populations — with the ramp in place these six controls ratio 0.0005..0.060;
+        // MEASURED populations — with the ramp in place these seven controls ratio 0.0005..0.060;
         // with it defeated (every live move delivered as a snap, run) they ratio 0.52..1.10.
         // The bound lands at 0.175: ~3x above the worst glide, ~3x below the tamest snap.
         const std::size_t rampFrames =
@@ -745,6 +753,7 @@ static void testPitchRatioAndVelocityGainStayLatched() {
     hostile.filterKeyTrack = 2.0;
     hostile.filterSettings.cutoffNorm = 0.0f;
     hostile.filterModAmount = 1.0;
+    hostile.filterVelAmount = 1.0;
     hostile.pitchEnv.shape.attackFrames = 4800;
     hostile.pitchEnv.shape.decayFrames = 4800;
     hostile.pitchEnv.peakSemitones = 24.0;