feat: auth screen with auto-redirect, sync favorites/history with backend

.agents/skills/vercel-react-native-skills/rules/ui-native-modals.md

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+---
+title: Use Native Modals Over JS-Based Bottom Sheets
+impact: HIGH
+impactDescription: native performance, gestures, accessibility
+tags: modals, bottom-sheet, native, react-navigation
+---
+
+## Use Native Modals Over JS-Based Bottom Sheets
+
+Use native `<Modal>` with `presentationStyle="formSheet"` or React Navigation
+v7's native form sheet instead of JS-based bottom sheet libraries. Native modals
+have built-in gestures, accessibility, and better performance. Rely on native UI
+for low-level primitives.
+
+**Incorrect (JS-based bottom sheet):**
+
+```tsx
+import BottomSheet from 'custom-js-bottom-sheet'
+
+function MyScreen() {
+  const sheetRef = useRef<BottomSheet>(null)
+
+  return (
+    <View style={{ flex: 1 }}>
+      <Button onPress={() => sheetRef.current?.expand()} title='Open' />
+      <BottomSheet ref={sheetRef} snapPoints={['50%', '90%']}>
+        <View>
+          <Text>Sheet content</Text>
+        </View>
+      </BottomSheet>
+    </View>
+  )
+}
+```
+
+**Correct (native Modal with formSheet):**
+
+```tsx
+import { Modal, View, Text, Button } from 'react-native'
+
+function MyScreen() {
+  const [visible, setVisible] = useState(false)
+
+  return (
+    <View style={{ flex: 1 }}>
+      <Button onPress={() => setVisible(true)} title='Open' />
+      <Modal
+        visible={visible}
+        presentationStyle='formSheet'
+        animationType='slide'
+        onRequestClose={() => setVisible(false)}
+      >
+        <View>
+          <Text>Sheet content</Text>
+        </View>
+      </Modal>
+    </View>
+  )
+}
+```
+
+**Correct (React Navigation v7 native form sheet):**
+
+```tsx
+// In your navigator
+<Stack.Screen
+  name='Details'
+  component={DetailsScreen}
+  options={{
+    presentation: 'formSheet',
+    sheetAllowedDetents: 'fitToContents',
+  }}
+/>
+```
+
+Native modals provide swipe-to-dismiss, proper keyboard avoidance, and
+accessibility out of the box.