feat(visualizer): controls row + unified MixVisualizerControlState; 3 inert uniforms wired (P10 W2)

DeepDrftPublic.Client/Controls/MixWaveformVisualizer.razor

@@ -11,23 +11,6 @@
     <canvas @ref="_canvas" class="mix-waveform-canvas"></canvas>
 </div>
 
-@* Viewing control only — never a seek surface. Hidden until a datum is present.
-   Deliberately a SIBLING of .mix-waveform-bg, not a child: the backdrop is position:fixed and so
-   forms its own stacking context, which would trap any descendant below the page's z-index:1
-   foreground (.mix-detail-foreground) and let that foreground swallow the slider's pointer events.
-   As a top-level sibling with its own z-index, the slider stacks above the foreground and stays
-   draggable. *@
-@if (_hasDatum)
-{
-    <div class="mix-waveform-zoom">
-        <MudSlider T="double"
-                   Value="@ZoomFraction"
-                   ValueChanged="@OnZoomFractionChanged"
-                   Min="0"
-                   Max="1"
-                   Step="0.001"
-                   Size="Size.Small"
-                   Color="Color.Primary"
-                   aria-label="Waveform zoom" />
-    </div>
-}
+@* The viewing controls (resolution + the three Wave 2 controls) live in MixVisualizerControls,
+   rendered in the mix-detail foreground row below the back button — NOT here. This component is now a
+   pure backdrop bridge; it pushes uniforms in response to the shared MixVisualizerControlState. *@