feat(mobile): track mobile app scaffold

mobile/app/src/components/ui/collapsible.tsx

@@ -0,0 +1,65 @@
+import { SymbolView } from 'expo-symbols';
+import { PropsWithChildren, useState } from 'react';
+import { Pressable, StyleSheet } from 'react-native';
+import Animated, { FadeIn } from 'react-native-reanimated';
+
+import { ThemedText } from '@/components/themed-text';
+import { ThemedView } from '@/components/themed-view';
+import { Spacing } from '@/constants/theme';
+import { useTheme } from '@/hooks/use-theme';
+
+export function Collapsible({ children, title }: PropsWithChildren & { title: string }) {
+  const [isOpen, setIsOpen] = useState(false);
+  const theme = useTheme();
+
+  return (
+    <ThemedView>
+      <Pressable
+        style={({ pressed }) => [styles.heading, pressed && styles.pressedHeading]}
+        onPress={() => setIsOpen((value) => !value)}>
+        <ThemedView type="backgroundElement" style={styles.button}>
+          <SymbolView
+            name={{ ios: 'chevron.right', android: 'chevron_right', web: 'chevron_right' }}
+            size={14}
+            weight="bold"
+            tintColor={theme.text}
+            style={{ transform: [{ rotate: isOpen ? '-90deg' : '90deg' }] }}
+          />
+        </ThemedView>
+
+        <ThemedText type="small">{title}</ThemedText>
+      </Pressable>
+      {isOpen && (
+        <Animated.View entering={FadeIn.duration(200)}>
+          <ThemedView type="backgroundElement" style={styles.content}>
+            {children}
+          </ThemedView>
+        </Animated.View>
+      )}
+    </ThemedView>
+  );
+}
+
+const styles = StyleSheet.create({
+  heading: {
+    flexDirection: 'row',
+    alignItems: 'center',
+    gap: Spacing.two,
+  },
+  pressedHeading: {
+    opacity: 0.7,
+  },
+  button: {
+    width: Spacing.four,
+    height: Spacing.four,
+    borderRadius: 12,
+    justifyContent: 'center',
+    alignItems: 'center',
+  },
+  content: {
+    marginTop: Spacing.three,
+    borderRadius: Spacing.three,
+    marginLeft: Spacing.four,
+    padding: Spacing.four,
+  },
+});