Fabric.js design canvas implementation and supporting infrastructure

Design Canvas (Primary)
- FabricDesignCanvasV2: Fabric.js-based product customization canvas
  - Lazy-loads Fabric.js to minimize bundle impact
  - Renders product mockup with print area guide (magenta dashed box)
  - Supports front/back view switching with correct product images
  - Color swatch selection for garment customization
  - Text element creation with selection handles and transform controls
  - Fixed React dependency array to prevent infinite renders

Support Components
- DesignCanvasWrapper: Client-side wrapper for SSR compatibility
- DesignCanvasErrorBoundary: Error boundary for canvas failures
- ThemeInitializer: Theme detection and application

Configuration
- Updated .claude/launch.json with dev server settings
- Updated .claude/settings.local.json with local preferences
- Updated next.config.mjs for production build optimization
- Dependency updates in package.json and package-lock.json

Known Issues & TODO
- Image element rendering disabled (Fabric.js compatibility investigation)
- Text editing UI controls needed (font, size, color pickers)
- Delete/undo functionality pending
- Print area alignment needs visual verification
- "Add to Cart" integration with design serialization pending

Testing Artifacts
- check_*.js: Product verification scripts for debugging

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

src/app/api/designs/[id]/send-to-customer/route.ts

@@ -4,13 +4,14 @@ import { sendDesignReadyForReview } from '@/lib/mail';
 
 export async function POST(
   req: Request,
-  { params }: { params: { id: string } }
+  { params }: { params: Promise<{ id: string }> }
 ) {
   try {
+    const { id } = await params;
     const { designPreviewUrl, designPreviewUrlBack, placementPreviewUrl, placementPreviewUrlBack } = await req.json().catch(() => ({}));
 
     const design = await prisma.designApproval.findUnique({
-      where: { id: params.id },
+      where: { id: id },
       include: { product: true },
     });
 
@@ -26,7 +27,7 @@ export async function POST(
     if (placementPreviewUrlBack) updateData.placementPreviewUrlBack = placementPreviewUrlBack;
 
     const updated = await prisma.designApproval.update({
-      where: { id: params.id },
+      where: { id: id },
       data: updateData,
       include: { product: true, messages: { orderBy: { createdAt: 'asc' } } },
     });
@@ -36,7 +37,7 @@ export async function POST(
       customerName: design.customerName || 'Customer',
       customerEmail: design.customerEmail,
       productName: design.product.name,
-      reviewLink: `${process.env.NEXT_PUBLIC_SITE_URL || 'http://localhost:3000'}/designs/${params.id}/review`,
+      reviewLink: `${process.env.NEXT_PUBLIC_SITE_URL || 'http://localhost:3000'}/designs/${id}/review`,
     });
 
     return NextResponse.json(updated);