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

lib/api/index.ts

@@ -0,0 +1,12 @@
+export * from './auth.api';
+export * from './user.api';
+export * from './group.api';
+export * from './banner.api';
+export * from './home.api';
+export * from './announcement.api';
+export * from './project.api';
+export * from './division.api';
+export * from './discussion.api';
+export * from './calendar.api';
+export * from './task.api';
+export * from './document.api';