feat(06-03): update display components to use categoryIcon with LucideIcon

- Rename categoryEmoji to categoryIcon in ItemCard, CandidateCard, ThreadCard, ItemPicker
- Import and render LucideIcon at appropriate sizes (36px placeholder, 14-16px badges)
- Update hook interfaces to match server API (categoryIcon instead of categoryEmoji)
- Rename iconData.ts to iconData.tsx (contains JSX)
- Update useCategories mutation type to use icon instead of emoji

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/client/hooks/useTotals.ts

@@ -4,7 +4,7 @@ import { apiGet } from "../lib/api";
 interface CategoryTotals {
   categoryId: number;
   categoryName: string;
-  categoryEmoji: string;
+  categoryIcon: string;
   totalWeight: number;
   totalCost: number;
   itemCount: number;