remove broken MudBlazor.ThemeManager 3.0.0 dependency — incompatible with MudBlazor 8.15.0, ThemeManagerTheme wrapper produced NRE in GenerateTheme; wire MudThemeProvider to DeepDrftPalettes.Default and hardcode AppBar Elevation=4

DeepDrftPublic.Client/Layout/MainLayout.razor

@@ -7,14 +7,14 @@
 @inherits LayoutComponentBase
 @implements IDisposable
 
-<MudThemeProvider Theme="@_themeManager.Theme" IsDarkMode="_isDarkMode" />
+<MudThemeProvider Theme="@DeepDrftPalettes.Default" IsDarkMode="_isDarkMode" />
 <MudPopoverProvider />
 <MudDialogProvider />
 <MudSnackbarProvider />
 <div class="@ThemeWrapperClass">
     <MudLayout Style="display: flex; flex-direction: column; min-height: 100vh">
         <AudioPlayerProvider>
-            <DeepDrftMenu Elevation="_themeManager.AppBarElevation" @bind-IsDarkMode="_isDarkMode" />
+            <DeepDrftMenu Elevation="4" @bind-IsDarkMode="_isDarkMode" />
             <MudMainContent Class="flex-grow-1 pt-16 pb-8">
                 <MudContainer MaxWidth="MaxWidth.False" Class="pa-4">
                     @Body
@@ -68,28 +68,6 @@
 
         // Register to persist state when prerendering completes
         _persistingSubscription = PersistentState.RegisterOnPersisting(PersistDarkMode);
-
-        // Palettes + typography live in DeepDrftShared.Client.Common.DeepDrftPalettes
-        // so the CMS host can reuse them. We wrap into ThemeManagerTheme to keep
-        // the MudBlazor.ThemeManager integration intact.
-        _themeManager = new ThemeManagerTheme
-        {
-            Theme = DeepDrftPalettes.Default,
-        };
-    }
-
-    private ThemeManagerTheme _themeManager;
-    public bool _themeManagerOpen = false;
-
-    void OpenThemeManager(bool value)
-    {
-        _themeManagerOpen = value;
-    }
-
-    void UpdateTheme(ThemeManagerTheme value)
-    {
-        _themeManager = value;
-        StateHasChanged();
     }
 
     // Theme wrapper class for CSS targeting