Fixes sajjadmrx#18

Add shadow to the widget similar to MacOS widgets.

* **src/arzChand/app.arzChand.tsx**
  - Add `boxShadow` property to the main container's style to apply a shadow to the entire widget.

* **src/setting/pages/arzChand/arzChand.setting.tsx**
  - Add a `Checkbox` component for enabling/disabling the shadow.
  - Update the `setSettingValue` function to handle the new shadow setting.
  - Update the `applyChanges` function to include the new shadow setting.

* **src/arzChand/component/currency.component.tsx**
  - Add state variables for `isTransparent` and `shadow`.
  - Add a `MutationObserver` to update `isTransparent` state based on body class changes.
  - Add an event listener for `updated-setting` to update the `shadow` state.
  - Apply the shadow setting to the currency items using inline styles.