Fix deck-UI review findings: right-anchor MASTER's meter column, correct stale/overclaiming comments, split test_deck_groups.cpp on its commit-tier/overlay seam, and pin two width-ceiling assertions.

src/core/instrument/ui/knob_deck.h

@@ -1,12 +1,8 @@
 // knob_deck.h — knob-deck layout + hit-test for the Sample-face knob deck. Engine-free
 // like param_slider: cells and toggles carry opaque shell-owned control ids. Mirror of
 // action_bar/param_slider; the knob primitive itself (value<->needle-angle, drag) is
-// param_slider's — a knob cell here is just a rect the shell composes it into.
-//
-// A group is a fenced box: caption row (caption left, toggles and a corner radio
-// right-anchored) over a knob row of equal-width cells, optionally followed by one row
-// toggle. Row membership is a PROPERTY OF THE GROUP (DeckRow), never a wrap outcome — see
-// the justification law at layoutDeck.
+// param_slider's — a knob cell here is just a rect the shell composes it into. Group/row
+// composition and the justification law are this directory's own CLAUDE.md's to describe.
 
 #pragma once
 
@@ -31,7 +27,8 @@ inline constexpr int kDeckGroupPadY = 4;      // group box vertical inner paddin
 inline constexpr int kDeckCaptionGap = 2;     // caption row -> knob row gap
 inline constexpr int kDeckToggleGap = 4;      // caption text -> toggle / cells -> row toggle gap
 inline constexpr int kDeckGroupGap = 12;      // gap between groups on a row
-inline constexpr int kDeckRowGap = 8;         // gap between wrapped deck rows
+inline constexpr int kDeckRowGap = 8;         // gap between the deck's two categorical rows,
+                                               // and between the spanning deck's stacked slots
 inline constexpr int kDeckRadioSize = 12;     // the caption-row corner radio square
 inline constexpr int kDeckColumnGap = 8;      // the spanning deck's cell column -> its readout column
 // The knob cell's INNER dial: a concentric sub-disc that edits a second, related value while
@@ -181,7 +178,8 @@ int deckHeight(const std::vector<DeckGroupDesc>& groups);
 // divided equally with the integer residue going to the leftmost ones. Decks are never
 // stretched. Below the width the block needs, every gutter sits at kDeckGroupGap and the row
 // overflows right rather than wrapping — the shell clamps the window to a floor that fits
-// (sample_bands' kEditorMinWidth), so that degrade is unreachable in the editor.
+// (sample_bands' kEditorMinWidth) via checkSizeConstraint, a host-honoured clamp rather than a
+// guarantee, so this degrade is defined and tested rather than assumed impossible.
 DeckLayout layoutDeck(const std::vector<DeckGroupDesc>& groups, int left, int top,
                       int availWidth);