Restructure the app into an Expo Router (tabs) group with a bottom navbar:
- 🎒 Cards (bag-personal) = the gallery (moved from app/index.tsx).
- 💰 Collectibles (sack) + 🤖 Agents (robot) = new empty-state screens.
- ⚙️ Settings (cog) = demo settings (app info + Clear all cards).
Root stack hides the (tabs) header; removed the Phase-1 (tabs)/cards.tsx and
pointed the dormant (auth)/login redirect at "/". localCardsStore gains clear().
Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>
