feat: full FrontOffice updates - discount store, blog, payment gateway, UI improvements

- Discount store pages (products, cart, orders, order detail)
- Blog pages and services
- Payment gateway callback page
- AppImage component, EmptyState, LoadingState, PageHeader
- DiscountCartService, DiscountOrderService, DiscountProductService
- BlogCategoryService, BlogPostService, SitePageService, ImageCacheService
- PhoneVerifyForm component
- Profile Hub page
- UI/UX improvements across all pages
- landing.js for homepage
- Config and routing updates

src/FrontOffice.Main/Shared/PageHeader.razor

@@ -0,0 +1,40 @@
+@inject NavigationManager Navigation
+@inject IJSRuntime JS
+
+<div class="page-header">
+    <MudStack Spacing="0">
+        <MudText Typo="Typo.h5">@Title</MudText>
+        @if (!string.IsNullOrWhiteSpace(Subtitle))
+        {
+            <MudText Typo="Typo.body2" Class="mud-text-secondary">@Subtitle</MudText>
+        }
+    </MudStack>
+    @if (ShowBack)
+    {
+        <MudButton Variant="Variant.Text" StartIcon="@Icons.Material.Filled.ArrowBack" OnClick="GoBack">بازگشت</MudButton>
+    }
+</div>
+
+@code {
+    [Parameter] public string Title { get; set; } = string.Empty;
+
+    /// <summary>
+    /// Optional subtitle text displayed below the title.
+    /// </summary>
+    [Parameter] public string? Subtitle { get; set; }
+    
+    /// <summary>
+    /// Fallback URL if there's no browser history. Uses history.back() first.
+    /// </summary>
+    [Parameter] public string? BackHref { get; set; }
+
+    /// <summary>
+    /// Whether to show the back button. Default is true.
+    /// </summary>
+    [Parameter] public bool ShowBack { get; set; } = true;
+
+    private async Task GoBack()
+    {
+        await JS.InvokeVoidAsync("history.back");
+    }
+}