fix(p15): remediate four green-minor review findings

Tokenize scrim navy RGB triple (--deepdrft-scrim-rgb); LAVA row now
flex-start so knobs group left; WAVE row keeps space-between for
right-pinned width knob; remove inert margin-left:auto/wvc-row-right;
correct stale seven->ten count in OnControlStateChanged comment.

DeepDrftPublic.Client/Controls/WaveformVisualizerControls.razor

@@ -82,7 +82,7 @@
             @* Color applies to the whole field regardless of which subsystems are on, so it is pinned
                far-right of row 1 and never reflows when collisions hides (§3). *@
             <MudTooltip Text="How fast the lamp drifts through its colors.">
-                <div class="waveform-visualizer-control mix-visualizer-control wvc-row-right" role="group" aria-label="Color gradient rotation speed">
+                <div class="waveform-visualizer-control mix-visualizer-control" role="group" aria-label="Color gradient rotation speed">
                     <RadialKnob Value="@ControlState.GradientRotationSpeed"
                                 ValueChanged="@OnGradientRotationSpeedChanged"
                                 Min="0" Max="1" Step="0.001"
@@ -148,7 +148,7 @@
         @* ── Row 3 — WAVE section (only when waveform on). Scroll is a SLIDER (§8); width pinned right. ── *@
         @if (ControlState.WaveformEnabled)
         {
-            <div class="wvc-row wvc-row-section">
+            <div class="wvc-row wvc-row-section wvc-row-wave">
                 <span class="wvc-section-label">WAVE:</span>
 
                 <MudTooltip Text="How fast the sound rolls by.">
@@ -163,7 +163,7 @@
                 </MudTooltip>
 
                 <MudTooltip Text="How wide the ribbon spreads across the lamp.">
-                    <div class="waveform-visualizer-control mix-visualizer-control wvc-row-right" role="group" aria-label="Waveform width">
+                    <div class="waveform-visualizer-control mix-visualizer-control" role="group" aria-label="Waveform width">
                         <RadialKnob Value="@ControlState.WaveformWidth"
                                     ValueChanged="@OnWaveformWidthChanged"
                                     Min="0" Max="1" Step="0.001"