refactor: pecah lib/api.ts dan constants/Styles.ts per domain

- lib/api.ts (879 baris) → 13 file di lib/api/ per domain
- constants/Styles.ts (1.275 baris) → 10 file di constants/styles/ per domain
- tambah docs/FILE-HEALTH.md dan referensinya ke CLAUDE.md
- kedua file lama tetap sebagai re-export — zero breaking changes

constants/styles/header.styles.ts

@@ -0,0 +1,23 @@
+import { StyleSheet } from "react-native";
+
+const HeaderStyles = StyleSheet.create({
+   headerContainer: { backgroundColor: '#19345E' },
+   headerApp: {
+      flexDirection: 'row',
+      alignItems: 'center',
+      justifyContent: 'space-between',
+      paddingHorizontal: 16,
+   },
+   headerTitle: { color: '#fff', fontSize: 18, fontWeight: '600' },
+   headerSide: { width: 40, alignItems: 'center' },
+   wrapHeadViewMember: {
+      backgroundColor: '#19345E',
+      paddingVertical: 30,
+      paddingHorizontal: 15,
+      alignItems: 'center',
+      borderBottomLeftRadius: 25,
+      borderBottomRightRadius: 25,
+   },
+});
+
+export default HeaderStyles;