Γ-W1-T1 review fixes: mode-independent taper rounding, sharper drag-step test, reset-sweep verifies stored fields

Swap nearbyint for std::round (MXCSR-independent); derive the finest-drag test
from the editor floor, not the knob; verify resets against fields, not norms;
record the spline-point modifier exclusion.

src/core/instrument/ui/deck_values.h

@@ -48,6 +48,16 @@ void setDeckParam(DeckParam id, PlaySeconds& play, double value, int segment);
 // For knob-valued controls — a toggle has no reset gesture.
 void resetDeckParam(DeckParam id, PlaySeconds& play);
 
+// The ADDRESS of the one stored field `id` owns — the mechanism resetDeckParam bypasses the taper
+// with. Exposed beyond that one caller so a test can verify a reset (or any other mutation)
+// against the actual stored field rather than its normalized read-back, which deckParamNorm does
+// not guarantee is injective. Null for a control with no reset gesture (a toggle, radio, or
+// curve-popup cell) or one whose value lives outside PlaySeconds (master gain, key-track).
+double* deckDoubleField(DeckParam id, PlaySeconds& p);
+// The filter's four tone controls store their normalized position as float — see deckFloatField's
+// definition for why that is a second resolver rather than a widened first one.
+float* deckFloatField(DeckParam id, PlaySeconds& p);
+
 // THE snap-unit table: which whole unit Shift snaps each control to. Includes the deck's
 // processor-side ids (voice count, master gain), which have no entry in the two functions above
 // because their VALUE lives outside the parameter set — the unit does not.