✨ 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/AuthLayout.razor

@@ -1,3 +1,98 @@
 @inherits LayoutComponentBase
+@inject MudThemeProvider MudThemeProvider
 
-@Body
+<MudThemeProvider @ref="mudThemeProvider" @bind-IsDarkMode="@isDarkMode" />
+
+<div class="auth-container">
+    <!-- Left Panel - Branding -->
+    <MudHidden Breakpoint="Breakpoint.SmAndDown" Invert="true" Class="auth-left-panel">
+        <div class="auth-branding">
+            <div class="auth-logo">
+                <MudIcon Icon="@Icons.Material.Filled.AnalyticsFill" Size="Size.Large" />
+            </div>
+            <MudText Typo="Typo.h3" Class="auth-title">
+                QuantEngine
+            </MudText>
+            <MudText Typo="Typo.body1" Class="auth-subtitle">
+                퇴직 자산 포트폴리오 관리 시스템
+            </MudText>
+            <div class="auth-features mt-8">
+                <div class="auth-feature">
+                    <MudIcon Icon="@Icons.Material.Filled.CheckCircle" />
+                    <MudText Typo="Typo.body2">실시간 자산 모니터링</MudText>
+                </div>
+                <div class="auth-feature">
+                    <MudIcon Icon="@Icons.Material.Filled.CheckCircle" />
+                    <MudText Typo="Typo.body2">AI 기반 분석</MudText>
+                </div>
+                <div class="auth-feature">
+                    <MudIcon Icon="@Icons.Material.Filled.CheckCircle" />
+                    <MudText Typo="Typo.body2">종합 보고서</MudText>
+                </div>
+            </div>
+        </div>
+
+        <!-- Dark Mode Toggle -->
+        <div class="auth-theme-toggle">
+            <MudIconButton Icon="@(isDarkMode ? Icons.Material.Filled.Brightness4 : Icons.Material.Filled.Brightness7)"
+                          Color="Color.Inherit"
+                          OnClick="ToggleDarkMode"
+                          Title="@(isDarkMode ? "라이트 모드" : "다크 모드")"
+                          Size="Size.Large" />
+        </div>
+    </MudHidden>
+
+    <!-- Right Panel - Auth Content -->
+    <div class="auth-right-panel">
+        <!-- Mobile Header -->
+        <MudHidden Breakpoint="Breakpoint.MdAndUp" Invert="true">
+            <div class="auth-mobile-header">
+                <MudText Typo="Typo.h5" Class="d-flex align-center">
+                    <MudIcon Icon="@Icons.Material.Filled.AnalyticsFill" Size="Size.Medium" Class="mr-2" />
+                    QuantEngine
+                </MudText>
+                <MudIconButton Icon="@(isDarkMode ? Icons.Material.Filled.Brightness4 : Icons.Material.Filled.Brightness7)"
+                              Color="Color.Inherit"
+                              OnClick="ToggleDarkMode"
+                              Title="@(isDarkMode ? "라이트 모드" : "다크 모드")" />
+            </div>
+        </MudHidden>
+
+        <!-- Content -->
+        <div class="auth-content">
+            @Body
+        </div>
+
+        <!-- Footer -->
+        <div class="auth-footer">
+            <MudText Typo="Typo.caption" Class="auth-footer-text">
+                © 2026 QuantEngine. 모든 권리 예약.
+            </MudText>
+            <div class="auth-footer-links">
+                <MudLink Href="/" Typo="Typo.caption">서비스 약관</MudLink>
+                <MudText Typo="Typo.caption">·</MudText>
+                <MudLink Href="/" Typo="Typo.caption">개인정보 처리방침</MudLink>
+            </div>
+        </div>
+    </div>
+</div>
+
+@code {
+    private MudThemeProvider mudThemeProvider = default!;
+    private bool isDarkMode = false;
+
+    protected override async Task OnAfterRenderAsync(bool firstRender)
+    {
+        if (firstRender)
+        {
+            isDarkMode = await mudThemeProvider.GetDarkModeAsync() ?? false;
+            StateHasChanged();
+        }
+    }
+
+    private async Task ToggleDarkMode()
+    {
+        isDarkMode = !isDarkMode;
+        await mudThemeProvider.SetDarkModeAsync(isDarkMode);
+    }
+}