fix(theme): green hero Share/Play/Queue glyphs in dark via shared .dd-accent-icon

Fold Session/Mix hero glyphs into the reusable accent-icon treatment so they reach
the glyph (beating .mud-secondary-text) green-accent in both themes; drop the dead
wrapper white rule and the redundant dark-only hero override. Light pixel-identical.

DeepDrftPublic.Client/Controls/ReleaseHeroOverlay.razor

@@ -52,7 +52,7 @@
         </MudStack>
         @if (ShareContent is not null)
         {
-            <div class="release-hero-share">
+            <div class="release-hero-share dd-accent-icon">
                 @ShareContent
             </div>
         }
@@ -74,7 +74,7 @@
             </div>
             @if (PlayContent is not null)
             {
-                <div class="release-hero-play">
+                <div class="release-hero-play dd-accent-icon">
                     @PlayContent
                 </div>
             }