bug: TextAreaInput missing visual feedback for disabled and readOnly states

[Kalpana-chavhan]

Description:

The TextAreaInput component lacks distinct visual styling when the disabled or readOnly props are applied. Currently, while the field becomes uneditable, it retains a white background, which is inconsistent with TextInput and other form elements that use a grey background (surface-disabled) to indicate inactivity.

Steps to reproduce:

1. Open Fuselage Storybook.
2. Navigate to Inputs/TextAreaInput.
3. Toggle the disabled control.
4. Observe that the background does not change color.

Expected behavior:

The component should use the standardized design tokens for disabled states, including a background color change and a not-allowed cursor.