Add a 'react-native' export condition routing Metro to a new src/index.native.ts that re-exports only the RN-safe leaf primitives (Button, Input, Textarea, Checkbox, Switch, Badge, Text, Heading, Card, Field, InputGroup, Stack, Inline, Cluster, Grid). The web index.ts barrel pulls react-dom (via Combobox) + web-only DOM APIs (Drawer/Dialog/Menu/Tabs/etc.), which crashes on native; those get RN variants in a later pass. Web resolution (Vite → dist) is unchanged; typecheck + build green.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>