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

CLAUDE.md

@@ -31,3 +31,7 @@ See @docs/ARCHITECTURE.md
 ## Key Conventions
 
 See @docs/CONVENTIONS.md
+
+## File Health
+
+See @docs/FILE-HEALTH.md