Add customer approval status messages and admin delete option

Customer-facing changes:
- Show approval status message when design is submitted
- Display pending approval notification with email confirmation
- Show approved confirmation when design is ready
- Show rejection message for designs needing changes

Admin-facing changes:
- Add delete button to design approval detail page
- Confirmation dialog before deletion
- Proper cleanup of design and associated messages
- Redirect to designs list after deletion

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

src/app/api/designs/[id]/route.ts

@@ -1,5 +1,6 @@
 import { NextResponse } from 'next/server';
 import { prisma } from '@/lib/prisma';
+import { getCurrentAdmin } from '@/lib/auth';
 
 export async function GET(
   req: Request,
@@ -24,3 +25,33 @@ export async function GET(
     );
   }
 }
+
+export async function DELETE(
+  req: Request,
+  { params }: { params: { id: string } }
+) {
+  try {
+    const admin = await getCurrentAdmin();
+    if (!admin) {
+      return NextResponse.json({ error: 'Unauthorized' }, { status: 401 });
+    }
+
+    // Delete associated messages first
+    await prisma.designApprovalMessage.deleteMany({
+      where: { designApprovalId: params.id },
+    });
+
+    // Delete the design approval
+    await prisma.designApproval.delete({
+      where: { id: params.id },
+    });
+
+    return NextResponse.json({ success: true });
+  } catch (err) {
+    console.error('Error deleting design:', err);
+    return NextResponse.json(
+      { error: 'Failed to delete design' },
+      { status: 500 }
+    );
+  }
+}