Add catalog item images with thumbnail preview in wizard

Each catalog item now supports one optional image (jpg/jpeg/png/gif/webp,
max 10 MB). Uploading generates a 200x200 JPEG thumbnail automatically via
SixLabors.ImageSharp. Images are stored in Azure Blob Storage under a new
catalogimages container, keyed by {companyId}/catalog/{itemId}/.

- CatalogItem entity: ImagePath + ThumbnailPath (nullable string fields)
- Migration: AddCatalogItemImages applied
- ICatalogImageService / CatalogImageService: upload, thumbnail generation,
  delete; old blobs replaced atomically on re-upload
- CatalogItemsController: Create/Edit accept optional IFormFile image;
  Image(id, thumbnail) action serves blobs with [Authorize] so wizard users
  can load thumbnails without CanManageProducts policy
- Catalog index (_CategoryNode): 40x40 thumbnail (or placeholder icon)
  left of each item name
- Details view: image card in right column with click-to-full-size link
- Create/Edit views: file picker with live preview; Edit shows current
  thumbnail with Remove checkbox
- Wizard (item-wizard.js): thumbnails in product list with hover preview
  that follows the cursor (showCatalogPreview / moveCatalogPreview);
  fixed Bootstrap d-flex !important bug that broke the filter box by
  moving flex layout to an inner wrapper div

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/PowderCoating.Application/Mappings/CatalogProfile.cs

@@ -92,7 +92,10 @@ namespace PowderCoating.Application.Mappings
                 .ForMember(dest => dest.IsDeleted, opt => opt.Ignore())
                 .ForMember(dest => dest.Category, opt => opt.Ignore())
                 .ForMember(dest => dest.RevenueAccount, opt => opt.Ignore())
-                .ForMember(dest => dest.CogsAccount, opt => opt.Ignore());
+                .ForMember(dest => dest.CogsAccount, opt => opt.Ignore())
+                // Image paths are set by CatalogImageService after the entity is saved, not from the DTO.
+                .ForMember(dest => dest.ImagePath, opt => opt.Ignore())
+                .ForMember(dest => dest.ThumbnailPath, opt => opt.Ignore());
 
             // UpdateCatalogItemDto -> CatalogItem
             CreateMap<UpdateCatalogItemDto, CatalogItem>()
@@ -104,7 +107,9 @@ namespace PowderCoating.Application.Mappings
                 .ForMember(dest => dest.IsDeleted, opt => opt.Ignore())
                 .ForMember(dest => dest.Category, opt => opt.Ignore())
                 .ForMember(dest => dest.RevenueAccount, opt => opt.Ignore())
-                .ForMember(dest => dest.CogsAccount, opt => opt.Ignore());
+                .ForMember(dest => dest.CogsAccount, opt => opt.Ignore())
+                .ForMember(dest => dest.ImagePath, opt => opt.Ignore())
+                .ForMember(dest => dest.ThumbnailPath, opt => opt.Ignore());
 
             // CatalogItem -> UpdateCatalogItemDto (reverse mapping for Edit)
             CreateMap<CatalogItem, UpdateCatalogItemDto>();