feat: Expo scaffold + auth screens + core screens (#39-#46, #48)

components/EmptyState.tsx

@@ -0,0 +1,32 @@
+import React from 'react';
+import { View, Text } from 'react-native';
+import { AppButton } from './AppButton';
+
+interface EmptyStateProps {
+  title: string;
+  description?: string;
+  actionLabel?: string;
+  onAction?: () => void;
+  icon?: string;
+}
+
+export const EmptyState: React.FC<EmptyStateProps> = ({
+  title,
+  description,
+  actionLabel,
+  onAction,
+  icon = '📭',
+}) => {
+  return (
+    <View className="flex-1 items-center justify-center px-8 py-16">
+      <Text className="text-5xl mb-4">{icon}</Text>
+      <Text className="text-lg font-semibold text-gray-800 text-center mb-2">{title}</Text>
+      {description && (
+        <Text className="text-sm text-gray-500 text-center mb-6">{description}</Text>
+      )}
+      {actionLabel && onAction && (
+        <AppButton title={actionLabel} onPress={onAction} className="min-w-[160px]" />
+      )}
+    </View>
+  );
+};