instrument: latch the note done at the read-head run-off, fit the migrated fades, and lift the curve dial and overlay selection into pure modules

src/core/instrument/ui/deck_groups.cpp

@@ -191,6 +191,32 @@ bool isLiveDeckParam(DeckParam id) {
     return false;  // unreachable for a valid enumerator; silences a warning.
 }
 
+OverlayEnv overlayEnvForRadio(int radioId) {
+    switch (static_cast<DeckParam>(radioId)) {
+        case DeckParam::kAmpEnvSelect:    return OverlayEnv::kAmp;
+        case DeckParam::kPitchEnvSelect:  return OverlayEnv::kPitch;
+        case DeckParam::kFilterEnvSelect: return OverlayEnv::kFilter;
+        default:                          return OverlayEnv::kNone;
+    }
+}
+
+OverlayEnv nextOverlaySelection(OverlayEnv current, int radioId) {
+    const OverlayEnv picked = overlayEnvForRadio(radioId);
+    if (picked == OverlayEnv::kNone) return current;  // not a radio: nothing selects
+    return (current == picked) ? OverlayEnv::kNone : picked;
+}
+
+bool overlayEnvInert(OverlayEnv env, bool pitchEnvEnabled, bool filterEnabled) {
+    switch (env) {
+        case OverlayEnv::kPitch:  return !pitchEnvEnabled;
+        case OverlayEnv::kFilter: return !filterEnabled;
+        case OverlayEnv::kAmp:
+        case OverlayEnv::kNone:
+            return false;
+    }
+    return false;  // unreachable for a valid enumerator; silences a warning.
+}
+
 bool liveCommitFor(LiveDragKind kind, int paramId) {
     switch (kind) {
         case LiveDragKind::kDeckKnob: