Update README: add backup/restore (encrypted local file, manual Drive copy), new deps

README.md

@@ -33,6 +33,8 @@ Android. Semua data tersimpan di perangkat (offline-first, tanpa server).
   - Ubah password aplikasi
   - Aktifkan/nonaktifkan login sidik jari (dengan dialog konfirmasi)
   - Atur session timeout
+  - **Backup & Restore**: export vault terenkripsi ke file lokal
+    (`Download/loginvault/*.enc`), restore dari file tersebut
   - Ganti tema: **Gelap (Dark)** atau **Sistem (System)**
 - **Menu Exit** — keluar dari aplikasi
 
@@ -49,7 +51,8 @@ lib/
 ├── theme_provider.dart     # theme mode (system/dark), persist via SharedPreferences
 ├── auth_screen.dart        # login/registrasi adaptif (email+password, bypass fingerprint)
 ├── dashboard_screen.dart   # search live, list, expand, swipe-delete, edit
-├── settings_screen.dart    # ubah password, tema, fingerprint, timeout, exit
+├── settings_screen.dart    # ubah password, tema, fingerprint, timeout, backup, exit
+├── backup_service.dart     # export/import encrypted vault file (local)
 ├── vault_entry_dialogs.dart# dialog add/edit/confirm
 └── main.dart               # entrypoint + routing + ThemeProvider
 ```
@@ -119,8 +122,18 @@ adb install build/app/outputs/flutter-apk/app-release.apk
    - Ubah password aplikasi
    - Aktifkan "Login dengan sidik jari" (muncul dialog konfirmasi; batal = tetap off)
    - Atur session timeout
+   - **Backup & Restore**:
+     - *Backup ke file (lokal)*: semua entri diekspor terenkripsi (pakai
+       password aplikasi) ke `Download/loginvault/loginvault_backup_<timestamp>.enc`
+     - *Restore dari file*: pilih file `.enc` dari folder tersebut → dikembalikan
+       ke DB (merge by id)
    - Ganti tema, atau Exit.
 
+> **Catatan backup:** File `.enc` **terenkripsi dengan password aplikasi**,
+> bukan constant key — aman jika dibagikan/copy ke Google Drive. Untuk survive
+> dari crash HP, copy file tersebut ke Google Drive (manual) atau simpan di
+> komputer. Restore butuh **password aplikasi yang sama** dengan saat backup.
+
 ---
 
 ## Dependencies utama
@@ -130,6 +143,8 @@ adb install build/app/outputs/flutter-apk/app-release.apk
 | `sqflite` | local database SQLite |
 | `flutter_secure_storage` | simpan email & password aplikasi (Keystore) |
 | `local_auth` | login dengan sidik jari (biometric Android) |
+| `path_provider` | akses folder Download (backup) |
+| `permission_handler` | izin storage (backup ke Download) |
 | `provider` | state management (theme) |
 | `shared_preferences` | persist tema & session timeout |
 | `crypto` | utilitas (tidak wajib, tersedia) |