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.Infrastructure/Migrations/20260425123256_AddCatalogItemImages.cs

@@ -0,0 +1,81 @@
+using System;
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace PowderCoating.Infrastructure.Migrations
+{
+    /// <inheritdoc />
+    public partial class AddCatalogItemImages : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.AddColumn<string>(
+                name: "ImagePath",
+                table: "CatalogItems",
+                type: "nvarchar(max)",
+                nullable: true);
+
+            migrationBuilder.AddColumn<string>(
+                name: "ThumbnailPath",
+                table: "CatalogItems",
+                type: "nvarchar(max)",
+                nullable: true);
+
+            migrationBuilder.UpdateData(
+                table: "PricingTiers",
+                keyColumn: "Id",
+                keyValue: 1,
+                column: "CreatedAt",
+                value: new DateTime(2026, 4, 25, 12, 32, 52, 295, DateTimeKind.Utc).AddTicks(5147));
+
+            migrationBuilder.UpdateData(
+                table: "PricingTiers",
+                keyColumn: "Id",
+                keyValue: 2,
+                column: "CreatedAt",
+                value: new DateTime(2026, 4, 25, 12, 32, 52, 295, DateTimeKind.Utc).AddTicks(5155));
+
+            migrationBuilder.UpdateData(
+                table: "PricingTiers",
+                keyColumn: "Id",
+                keyValue: 3,
+                column: "CreatedAt",
+                value: new DateTime(2026, 4, 25, 12, 32, 52, 295, DateTimeKind.Utc).AddTicks(5156));
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropColumn(
+                name: "ImagePath",
+                table: "CatalogItems");
+
+            migrationBuilder.DropColumn(
+                name: "ThumbnailPath",
+                table: "CatalogItems");
+
+            migrationBuilder.UpdateData(
+                table: "PricingTiers",
+                keyColumn: "Id",
+                keyValue: 1,
+                column: "CreatedAt",
+                value: new DateTime(2026, 4, 24, 23, 28, 22, 104, DateTimeKind.Utc).AddTicks(7155));
+
+            migrationBuilder.UpdateData(
+                table: "PricingTiers",
+                keyColumn: "Id",
+                keyValue: 2,
+                column: "CreatedAt",
+                value: new DateTime(2026, 4, 24, 23, 28, 22, 104, DateTimeKind.Utc).AddTicks(7162));
+
+            migrationBuilder.UpdateData(
+                table: "PricingTiers",
+                keyColumn: "Id",
+                keyValue: 3,
+                column: "CreatedAt",
+                value: new DateTime(2026, 4, 24, 23, 28, 22, 104, DateTimeKind.Utc).AddTicks(7164));
+        }
+    }
+}

src/PowderCoating.Infrastructure/Migrations/ApplicationDbContextModelSnapshot.cs

@@ -1416,6 +1416,9 @@ namespace PowderCoating.Infrastructure.Migrations
                     b.Property<int>("DisplayOrder")
                         .HasColumnType("int");
 
+                    b.Property<string>("ImagePath")
+                        .HasColumnType("nvarchar(max)");
+
                     b.Property<int?>("InventoryItemId")
                         .HasColumnType("int");
 
@@ -1438,6 +1441,9 @@ namespace PowderCoating.Infrastructure.Migrations
                     b.Property<string>("SKU")
                         .HasColumnType("nvarchar(max)");
 
+                    b.Property<string>("ThumbnailPath")
+                        .HasColumnType("nvarchar(max)");
+
                     b.Property<DateTime?>("UpdatedAt")
                         .HasColumnType("datetime2");
 
@@ -5776,7 +5782,7 @@ namespace PowderCoating.Infrastructure.Migrations
                         {
                             Id = 1,
                             CompanyId = 0,
-                            CreatedAt = new DateTime(2026, 4, 24, 23, 28, 22, 104, DateTimeKind.Utc).AddTicks(7155),
+                            CreatedAt = new DateTime(2026, 4, 25, 12, 32, 52, 295, DateTimeKind.Utc).AddTicks(5147),
                             Description = "Standard pricing for regular customers",
                             DiscountPercent = 0m,
                             IsActive = true,
@@ -5787,7 +5793,7 @@ namespace PowderCoating.Infrastructure.Migrations
                         {
                             Id = 2,
                             CompanyId = 0,
-                            CreatedAt = new DateTime(2026, 4, 24, 23, 28, 22, 104, DateTimeKind.Utc).AddTicks(7162),
+                            CreatedAt = new DateTime(2026, 4, 25, 12, 32, 52, 295, DateTimeKind.Utc).AddTicks(5155),
                             Description = "5% discount for preferred customers",
                             DiscountPercent = 5m,
                             IsActive = true,
@@ -5798,7 +5804,7 @@ namespace PowderCoating.Infrastructure.Migrations
                         {
                             Id = 3,
                             CompanyId = 0,
-                            CreatedAt = new DateTime(2026, 4, 24, 23, 28, 22, 104, DateTimeKind.Utc).AddTicks(7164),
+                            CreatedAt = new DateTime(2026, 4, 25, 12, 32, 52, 295, DateTimeKind.Utc).AddTicks(5156),
                             Description = "10% discount for premium customers",
                             DiscountPercent = 10m,
                             IsActive = true,

src/PowderCoating.Infrastructure/PowderCoating.Infrastructure.csproj

@@ -21,6 +21,7 @@
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>
     <PackageReference Include="SendGrid" Version="9.29.3" />
+    <PackageReference Include="SixLabors.ImageSharp" Version="3.1.12" />
     <PackageReference Include="Stripe.net" Version="50.4.1" />
     <PackageReference Include="Twilio" Version="7.14.3" />
   </ItemGroup>