style(track-card): glass theming — remove MudBlazor color overrides, add theme-scoped CSS for title/artist/meta hierarchy and navy-glass fallback panel

DeepDrftShared.Client/Components/TrackCard.razor

@@ -1,5 +1,5 @@
 <MudCard Class="deepdrft-track-card-container"
-         Elevation="4">
+         Elevation="0">
 
     @if (!string.IsNullOrEmpty(TrackModel?.ImagePath))
     {
@@ -8,7 +8,7 @@
     }
     else
     {
-        <MudPaper Class="deepdrft-track-card-fallback mud-theme-secondary"
+        <MudPaper Class="deepdrft-track-card-fallback"
                   Elevation="0">
         </MudPaper>
     }
@@ -17,14 +17,12 @@
 
         <div class="deepdrft-track-info-top">
             <MudText Typo="Typo.subtitle1"
-                     Color="Color.Surface"
-                     Class="text-truncate mb-1">
+                     Class="deepdrft-track-title text-truncate mb-1">
                 @TrackModel?.TrackName
             </MudText>
 
             <MudText Typo="Typo.caption"
-                     Color="Color.Surface"
-                     Class="text-truncate mb-2">
+                     Class="deepdrft-track-artist text-truncate mb-2">
                 @TrackModel?.Artist
             </MudText>
         </div>
@@ -33,8 +31,7 @@
             @if (!string.IsNullOrEmpty(TrackModel?.Album))
             {
                 <MudText Typo="Typo.caption"
-                         Color="Color.Surface"
-                         Class="text-truncate">
+                         Class="deepdrft-track-meta text-truncate">
                     @TrackModel.Album
                 </MudText>
             }
@@ -55,7 +52,7 @@
             @if (TrackModel?.ReleaseDate.HasValue == true)
             {
                 <MudText Typo="Typo.caption"
-                         Color="Color.Surface">
+                         Class="deepdrft-track-meta">
                     @TrackModel.ReleaseDate.Value.Year
                 </MudText>
             }