feat(ST-507): show code badges on cards, lists and dialogs across the app

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

components/backlog/pbi-list.tsx

@@ -49,6 +49,7 @@ const PRIORITY_COLORS: Record<number, string> = {
 
 interface Pbi {
   id: string
+  code: string | null
   title: string
   priority: number
   description?: string | null
@@ -92,6 +93,7 @@ function SortablePbiRow({
       {...attributes}
       {...listeners}
       title={pbi.title}
+      code={pbi.code}
       priority={pbi.priority}
       isSelected={isSelected}
       isDragging={isDragging}