filter: sweep the corner continuously; raise the editor floor to 840x620

Cutoff-only re-solve (15.5 vs 56.9 ns/frame) makes the unquantized sweep
affordable, replacing the 2048-step mod quantizer. Live-compute parameters
remain blocked on a shell-architecture ruling.

tests/test_knob_deck.cpp

@@ -4,9 +4,8 @@
 //  * group width — caption row vs knob row max + padding; row-toggle and caption-toggle widths.
 //  * layout — caption toggle right-anchored IN the caption row; cells fixed 48x58 left-to-right
 //    inside the box; knob square centered; label band beneath; row toggle after the cells.
-//  * wrap — deterministic whole-group wrap at a narrowing width (the r11 "PITCH ENV onto row
-//    two at the 560 floor" behavior); the first group of a row always places; deckHeight
-//    consistency with deckRowCount.
+//  * wrap — deterministic whole-group wrap at a narrowing width; the first group of a row
+//    always places; deckHeight consistency with deckRowCount.
 //  * hit-test — knob cell hit (whole cell), toggle segment 0/1 boundaries, blank (-1) cells
 //    and fence padding miss, outside-deck miss.
 
@@ -52,8 +51,9 @@ static void testGroupWidth() {
 }
 
 static void testWrapAtNarrowWidthIsDeterministic() {
-    // At the 560x460 checkSizeConstraint floor (544 available) the deck wraps to TWO rows,
-    // whole trailing groups only.
+    // A width that forces this synthetic deck to wrap: TWO rows, whole trailing groups only.
+    // Deliberately narrower than the shipped editor floor — this pins the wrap MECHANISM, not
+    // the shipped deck's row count (that is deck_groups' own test).
     const auto deck = shellLikeDeck();
     CHECK(deckRowCount(deck, 544) == 2);
     CHECK(deckHeight(deck, 544) == 2 * kDeckGroupH + kDeckRowGap);