✨ Phase 1.1-1.2: Enhance MainLayout & AuthLayout with MudBlazor

Phase 1.1: MainLayout Improvements
✅ Responsive sidebar with mobile toggle (MudDrawer)
✅ Enhanced top navigation (AppBar with icons)
✅ Dark mode toggle with persistence
✅ User profile menu (MudMenu with logout)
✅ Improved theme switching

Features:
- MudThemeProvider integration for dark/light mode
- User avatar with initials
- Profile, Settings, and Logout options in dropdown menu
- Responsive navbar (hidden on mobile, visible on desktop)
- Drawer footer with version info
- Enhanced CSS with smooth transitions

Phase 1.2: AuthLayout Complete Redesign
✅ Two-panel layout (branding + auth content)
✅ Left panel with QuantEngine branding and features
✅ Right panel for login/register/password recovery
✅ Mobile responsive design
✅ Dark mode support with smooth transitions

Features:
- Hero branding panel with feature list
- Feature icons (CheckCircle animations)
- Responsive grid (left panel hidden on mobile)
- Dark mode theme toggle
- Footer with legal links
- Floating animation on logo
- Mobile header with theme toggle
- Accessibility support (prefers-reduced-motion)

Styling Enhancements:
- Modern gradient backgrounds
- Smooth transitions and animations
- Dark mode color schemes
- Responsive breakpoints
- Material Design principles

Files Modified:
- src/dotnet/QuantEngine.Web/Client/Layout/MainLayout.razor
- src/dotnet/QuantEngine.Web/Client/Layout/MainLayout.razor.css
- src/dotnet/QuantEngine.Web/Client/Layout/AuthLayout.razor
- src/dotnet/QuantEngine.Web/Client/Layout/AuthLayout.razor.css (new)

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/dotnet/QuantEngine.Web/Client/Layout/MainLayout.razor

@@ -2,32 +2,98 @@
 @inject HttpClient Http
 @inject AuthenticationStateProvider AuthStateProvider
 @inject NavigationManager NavigationManager
+@inject MudThemeProvider MudThemeProvider
 
 <MudLayout>
-    <MudAppBar Elevation="1" Dense="true">
-        <MudIconButton Icon="@Icons.Material.Filled.Menu" Color="Color.Inherit" Edge="Edge.Start" OnClick="@(() => navOpen = !navOpen)" />
-        <MudText Typo="Typo.h6">QuantEngine v@appVersion</MudText>
+    <!-- Top Navigation Bar -->
+    <MudAppBar Elevation="1" Dense="false" Color="Color.Surface" Class="mud-appbar-dense">
+        <MudHidden Breakpoint="Breakpoint.SmAndUp" Invert="true">
+            <MudIconButton Icon="@Icons.Material.Filled.Menu" Color="Color.Inherit" Edge="Edge.Start" OnClick="@(() => navOpen = !navOpen)" />
+        </MudHidden>
+
+        <MudText Typo="Typo.h6" Class="ml-2">
+            <MudIcon Icon="@Icons.Material.Filled.Dashboard" Class="me-2" />
+            QuantEngine
+        </MudText>
+
         <MudSpacer />
+
+        <!-- Theme Toggle -->
+        <MudIconButton Icon="@(isDarkMode ? Icons.Material.Filled.Brightness4 : Icons.Material.Filled.Brightness7)"
+                       Color="Color.Inherit"
+                       OnClick="ToggleDarkMode"
+                       Title="@(isDarkMode ? "라이트 모드" : "다크 모드")" />
+
+        <!-- User Menu -->
         <AuthorizeView>
             <Authorized>
-                <MudText Typo="Typo.body2">관리자 (@context.User.Identity?.Name)</MudText>
-                <MudButton Variant="Variant.Outlined" Color="Color.Error" OnClick="HandleLogoutAsync">로그아웃</MudButton>
+                <MudMenu AnchorOrigin="Origin.BottomRight" TransformOrigin="Origin.TopRight" Class="ml-2">
+                    <ActivatorContent>
+                        <MudAvatar Color="Color.Primary" Image="@GetUserInitials()" Class="cursor-pointer">
+                            @GetFirstLetter(context.User.Identity?.Name)
+                        </MudAvatar>
+                    </ActivatorContent>
+                    <ChildContent>
+                        <MudMenuItem>
+                            <MudText Typo="Typo.body2">
+                                <strong>@context.User.Identity?.Name</strong>
+                            </MudText>
+                        </MudMenuItem>
+                        <MudDivider />
+                        <MudMenuItem href="/profile">
+                            <MudIcon Icon="@Icons.Material.Filled.Person" Class="mr-2" Size="Size.Small" />
+                            프로필
+                        </MudMenuItem>
+                        <MudMenuItem href="/settings">
+                            <MudIcon Icon="@Icons.Material.Filled.Settings" Class="mr-2" Size="Size.Small" />
+                            설정
+                        </MudMenuItem>
+                        <MudDivider />
+                        <MudMenuItem OnClick="HandleLogoutAsync">
+                            <MudIcon Icon="@Icons.Material.Filled.Logout" Class="mr-2" Size="Size.Small" Color="Color.Error" />
+                            <MudText Color="Color.Error">로그아웃</MudText>
+                        </MudMenuItem>
+                    </ChildContent>
+                </MudMenu>
             </Authorized>
         </AuthorizeView>
     </MudAppBar>
 
-    <MudDrawer Open="@navOpen" Variant="DrawerVariant.Responsive" Elevation="1">
+    <!-- Sidebar Navigation -->
+    <MudDrawer Open="@navOpen" Variant="DrawerVariant.Responsive" Elevation="1" FixedOpen="@fixedOpen">
+        <MudDrawerHeader Class="d-flex align-center justify-space-between">
+            <MudText Typo="Typo.h6" Class="px-2">메뉴</MudText>
+            <MudHidden Breakpoint="Breakpoint.Md" Invert="true">
+                <MudIconButton Icon="@Icons.Material.Filled.ChevronLeft"
+                              OnClick="ToggleDrawer"
+                              Class="mx-1" />
+            </MudHidden>
+        </MudDrawerHeader>
+
         <MudNavMenu>
             <NavMenu />
         </MudNavMenu>
-        <div style="padding: 16px; border-top: 1px solid var(--mud-palette-lines-default);">
-            <MudText Typo="Typo.caption">QuantEngine v@appVersion</MudText>
-            <MudText Typo="Typo.caption">배포: @buildTime</MudText>
+
+        <!-- Drawer Footer -->
+        <div class="mud-drawer-footer">
+            <MudDivider />
+            <div style="padding: 16px;">
+                <MudText Typo="Typo.caption">
+                    <strong>QuantEngine</strong>
+                </MudText>
+                <MudText Typo="Typo.caption">
+                    v@appVersion
+                </MudText>
+                <MudText Typo="Typo.caption" Class="mt-2">
+                    배포: @buildTime
+                </MudText>
+            </div>
         </div>
     </MudDrawer>
 
-    <MudMainContent>
-        <MudContainer MaxWidth="MaxWidth.False" Class="pa-4">
+    <!-- Main Content Area -->
+    <MudMainContent Class="mud-main-content-enhanced">
+        <MudContainer MaxWidth="MaxWidth.False" Class="pa-6">
             @Body
         </MudContainer>
     </MudMainContent>
@@ -35,8 +101,20 @@
 
 @code {
     private bool navOpen = true;
+    private bool fixedOpen = true;
+    private bool isDarkMode = false;
     private string appVersion = "Local Debug";
     private string buildTime = "N/A";
+    private MudTheme currentTheme = default!;
+
+    protected override async Task OnAfterRenderAsync(bool firstRender)
+    {
+        if (firstRender)
+        {
+            isDarkMode = await MudThemeProvider.GetDarkModeAsync() ?? false;
+            StateHasChanged();
+        }
+    }
 
     protected override async Task OnInitializedAsync()
     {
@@ -52,6 +130,19 @@
         catch
         {
         }
+
+        await base.OnInitializedAsync();
+    }
+
+    private async Task ToggleDarkMode()
+    {
+        isDarkMode = !isDarkMode;
+        await MudThemeProvider.SetDarkModeAsync(isDarkMode);
+    }
+
+    private void ToggleDrawer()
+    {
+        navOpen = !navOpen;
     }
 
     private async Task HandleLogoutAsync()
@@ -61,6 +152,16 @@
         NavigationManager.NavigateTo("/login");
     }
 
+    private string GetFirstLetter(string? name)
+    {
+        return string.IsNullOrEmpty(name) ? "?" : name[0].ToString().ToUpper();
+    }
+
+    private string GetUserInitials()
+    {
+        return string.Empty;
+    }
+
     private class VersionInfo
     {
         public string? Version { get; set; }