NextNav
Deployable navigation framework with groups, optional subcategories, and entry pages.

URL patterns
- /zh, /en — home with featured picks
- /zh/ai — group hub (when subcategories exist)
- /zh/tools — leaf group list (no subcategories)
- /zh/ai/chu-jing-tou — subcategory list
- /zh/ai/chu-jing-tou/domoai — entry detail
- /zh/tools/{entry} — entry on a leaf group (when added)

Demo groups
- AI (ai): four sample subcategories under /zh/ai
- Tools (tools): leaf group, empty list for now

Featured items: edit homeFeatured in data/catalog.ts (admin later).