Reflow the deck into two categorical rows plus a double-height MASTER bus deck

Row membership is now the group's own property, not a wrap outcome. FILTER's Band|Notch moves to its caption slack, which is what makes the sound row fit. MASTER gains the limiter toggle, the output meter and the GR lamp.

tests/test_sample_bands.cpp

@@ -131,10 +131,10 @@ static void testDeckBandIsBottomAnchoredAtTheEditorFloor() {
     CHECK(b.decks.bottom() == kEditorMinHeight - kPad);
 }
 
-// At a representative two-row deck height (216px — the ceiling test_deck_groups.cpp bounds
-// the wrapped deck to), the waveform gets exactly what the floor's own height leaves it: an
-// equality, not a bound, so a floor-height change that quietly ate into the waveform's slack
-// would fail here rather than only widen/narrow a `>=`.
+// At the shipped two-row deck height (216px — what test_deck_groups.cpp pins the deck to by
+// construction, at and above the floor width), the waveform gets exactly what the floor's own
+// height leaves it: an equality, not a bound, so a floor-height change that quietly ate into
+// the waveform's slack would fail here rather than only widen/narrow a `>=`.
 static void testWaveformGetsExactlyTheFloorsRemainingHeightAtATwoRowDeck() {
     constexpr int twoRowDeckH = 216;
     const SampleBands b = computeSampleBands(kEditorMinWidth, kEditorMinHeight, twoRowDeckH);