Enable Language setting in Settings screen

[Noro18]

Description

The "Language" setting allows users to change the app language. Currently commented out and only shows a Toast — not actually functional.

File: `app/src/main/java/com/example/ordermanagementcake/ui/settings/SettingsScreen.kt` (lines 112-114)

Expected Behavior

Users can select a language from the dialog and the app switches to that language immediately (or on restart).

Implementation

1. Uncomment the `SettingsItem("Language", ...)` entry in `preferenceItems`.
2. Replace the Toast in `LanguageDialog.onLanguageSelected` with actual locale switching logic.
3. Persist the selected language preference using `DataStore` or `SharedPreferences`.
4. On app launch, read the saved locale and apply it via `LocaleListCompat` (from AndroidX AppCompat) or custom configuration override.
5. Update the apps `Context.createConfigurationContext()` or use `AppCompatDelegate.setApplicationLocales()` to apply the change.
6. Consider adding a default/system option to revert to the device locale.

Additional Context

• `LanguageDialog` exists at `app/src/main/java/com/example/ordermanagementcake/ui/setting_options/LanguageDialog.kt` — review and update as needed.
• Ensure string resources exist for all supported languages (Tetum, Portuguese, English, etc.).