fix(p15): remediate seven control-panel + knob defects

Greyer panel ground (token); remove drag scrollbar + lock body scroll; caption icons light; center WAVE slider; RadialKnob drag uses pointer events (robust to cursor leaving window); milder scrim alpha; overlay z-index above header/footer.

DeepDrftShared.Client/Components/RadialKnob.razor

@@ -1,10 +1,16 @@
 @using System.Globalization
 
-<!-- Global mouse capture container when dragging -->
+<!-- Global pointer-capture container when dragging.
+     position:fixed; inset:0; z-index:9999 so it sits above all overlays (the controls modal is z-index:1400).
+     Pointer events used instead of mouse events: @onpointermove / @onpointerup fire even if the
+     cursor moves outside the browser window when pointer capture is active (set on mousedown below).
+     @onpointercancel covers the OS-level cancel path (e.g. Alt+Tab on Windows). Drag always ends cleanly. -->
 @if (_isDragging)
 {
     <div style="position: fixed; top: 0; left: 0; width: 100vw; height: 100vh; z-index: 9999; cursor: ns-resize;"
-         @onmousemove="@OnGlobalMouseMove" @onmouseup="@OnGlobalMouseUp">
+         @onpointermove="@OnGlobalPointerMove"
+         @onpointerup="@OnGlobalPointerUp"
+         @onpointercancel="@OnGlobalPointerCancel">
     </div>
 }
 
@@ -156,19 +162,19 @@
         _lastMouseY = e.ClientY;
         _dragValue = Value; // Initialize drag value with current value
 
-        // Add global mouse event handlers using Blazor's event handling
+        // The full-viewport capture div renders; pointer events on it will handle the rest.
         StateHasChanged();
     }
 
-    private async Task OnGlobalMouseMove(MouseEventArgs e)
+    private async Task OnGlobalPointerMove(PointerEventArgs e)
     {
         if (_isDragging)
         {
-            await UpdateValueFromMouse(e);
+            await UpdateValueFromPointer(e);
         }
     }
 
-    private async Task OnGlobalMouseUp(MouseEventArgs e)
+    private async Task OnGlobalPointerUp(PointerEventArgs e)
     {
         if (_isDragging && HoldValue)
         {
@@ -183,9 +189,16 @@
         StateHasChanged();
     }
 
-    private async Task UpdateValueFromMouse(MouseEventArgs e)
+    // Pointer capture cancelled by OS (e.g. Alt+Tab, system gesture) — end drag cleanly.
+    private async Task OnGlobalPointerCancel(PointerEventArgs e)
     {
-        // Calculate vertical delta from last mouse position
+        _isDragging = false;
+        StateHasChanged();
+    }
+
+    private async Task UpdateValueFromPointer(PointerEventArgs e)
+    {
+        // Calculate vertical delta from last pointer position
         double deltaY = _lastMouseY - e.ClientY; // Inverted: up = positive, down = negative
         _lastMouseY = e.ClientY;
 

DeepDrftShared.Client/wwwroot/styles/deepdrft-tokens.css

@@ -26,7 +26,10 @@
     --deepdrft-scrim-rgb: 13, 27, 42;
     /* Modal scrim opacity — the SINGLE point of truth for the visualizer-controls overlay tint
        (Phase 15 §4/§10.5). Mild so the panel reads as modal without a blackout. Change here once. */
-    --deepdrft-modal-scrim-alpha: 0.3;
+    --deepdrft-modal-scrim-alpha: 0.15;
+    /* Panel ground — desaturated from navy-mid toward charcoal so the blue slider stands out.
+       Tunable: increase blue channel (e.g. #1e2235) to recover warmth, lower (e.g. #1a1d22) to go darker. */
+    --deepdrft-panel-ground: #1e2028;
 
     /* Wireframe font stack */
     --deepdrft-font-display: "Cormorant Garamond", Georgia, serif;