Widen the deck row block to 1028 so the filter tie-line is exact, and accumulate the meter's block peaks instead of sampling one in 47

src/core/instrument/ui/knob_deck.h

@@ -57,10 +57,14 @@ enum class DeckRow { Sound, Contour, Spanning };
 // from the first two — kDeckRowBlockW + kDeckGroupGap + kDeckSpanningW + 2*kPad — and the
 // identity is asserted in test_deck_groups.cpp rather than coded, so the allocator keeps no
 // include edge to this header.
-inline constexpr int kDeckRowBlockW = 1020;  // the block both categorical rows justify inside
+// 1028 is the width at which the justification law puts BOTH rows' filter groups on the same
+// right edge (x = 640 block-relative) AND divides row 1's slack into three equal gutters. The
+// narrower 1020 delivered neither: 40 px over three gutters is 13⅓, so the law produced
+// 14/13/13 and left row 1's filter edge 2 px past row 2's.
+inline constexpr int kDeckRowBlockW = 1028;  // the block both categorical rows justify inside
 inline constexpr int kDeckSpanningW = 142;   // the right-anchored spanning deck, outside the block
 // The hard ceiling the floor may not exceed lives beside the floor itself, in sample_bands.h's
-// kEditorCeilingWidth — a window fact, not a deck one. Today's gap between the two is 90px,
+// kEditorCeilingWidth — a window fact, not a deck one. Today's gap between the two is 82px,
 // the whole width budget for the life of this layout (asserted in test_deck_groups.cpp) — see
 // instrument-control-surface.md §1.6 before spending any of it.