feat(plans): menu watermark on Free (removed by paid feature)

Guest QR menu shows a "ساخته‌شده با میزی" watermark under the menu unless the café's
plan has the `watermark_removed` feature (Starter+).

- PublicMenuDto gains ShowWatermark; PublicService computes it from
  IsFeatureEnabledForCafeAsync("watermark_removed") for both slug and branch menus.
- Guest menu renders the watermark footer when showWatermark.
- NoOpPlatformCatalogService test double (all features on) for the PublicService
  ctor; QrMenuTests updated.

86 tests pass; dashboard tsc clean.

src/Meezi.API/Models/Public/PublicDtos.cs

@@ -107,7 +107,8 @@ public record PublicMenuDto(
     string CafeName,
     string Slug,
     CafeThemeDto Theme,
-    IReadOnlyList<PublicMenuCategoryDto> Categories);
+    IReadOnlyList<PublicMenuCategoryDto> Categories,
+    bool ShowWatermark);
 
 public record GuestCreateOrderRequest(
     OrderType OrderType,

src/Meezi.API/Services/PublicService.cs

@@ -53,6 +53,7 @@ public class PublicService : IPublicService
     private readonly IBranchIdentityService _identity;
     private readonly IAbuseProtectionService _abuse;
     private readonly IHttpContextAccessor _http;
+    private readonly Meezi.Infrastructure.Services.Platform.IPlatformCatalogService _catalog;
 
     public PublicService(
         AppDbContext db,
@@ -62,7 +63,8 @@ public class PublicService : IPublicService
         IBranchMenuService branchMenu,
         IBranchIdentityService identity,
         IAbuseProtectionService abuse,
-        IHttpContextAccessor http)
+        IHttpContextAccessor http,
+        Meezi.Infrastructure.Services.Platform.IPlatformCatalogService catalog)
     {
         _db = db;
         _orders = orders;
@@ -72,8 +74,13 @@ public class PublicService : IPublicService
         _identity = identity;
         _abuse = abuse;
         _http = http;
+        _catalog = catalog;
     }
 
+    /// <summary>Free menus show a Meezi watermark; the `watermark_removed` feature (paid) hides it.</summary>
+    private async Task<bool> ShowWatermarkAsync(Cafe cafe, CancellationToken ct) =>
+        !await _catalog.IsFeatureEnabledForCafeAsync(cafe.Id, cafe.PlanTier, "watermark_removed", ct);
+
     public Task<IReadOnlyList<CafeDiscoverDto>> DiscoverAsync(
         DiscoverFilterParams filters,
         CancellationToken cancellationToken = default) =>
@@ -190,7 +197,8 @@ public class PublicService : IPublicService
             .Where(c => c.Items.Count > 0)
             .ToList();
 
-        return new PublicMenuDto(cafe.Id, cafe.Name, cafe.Slug, CafeThemeMapping.FromJson(cafe.ThemeJson), grouped);
+        return new PublicMenuDto(cafe.Id, cafe.Name, cafe.Slug, CafeThemeMapping.FromJson(cafe.ThemeJson), grouped,
+            await ShowWatermarkAsync(cafe, cancellationToken));
     }
 
     public async Task<(GuestOrderPlacedDto? Data, string? ErrorCode, string? ErrorMessage)> PlaceOrderAsync(
@@ -357,7 +365,8 @@ public class PublicService : IPublicService
             .OrderBy(c => categoryById.GetValueOrDefault(c.Id)?.SortOrder ?? 0)
             .ToList();
 
-        return new PublicMenuDto(cafe.Id, cafe.Name, cafe.Slug, CafeThemeMapping.FromJson(cafe.ThemeJson), grouped);
+        return new PublicMenuDto(cafe.Id, cafe.Name, cafe.Slug, CafeThemeMapping.FromJson(cafe.ThemeJson), grouped,
+            await ShowWatermarkAsync(cafe, cancellationToken));
     }
 
     public async Task<(GuestQrOrderPlacedDto? Data, string? ErrorCode, string? Message)> PlaceBranchGuestOrderAsync(