chore: refactor UI consistency using design system tokens and remove LucideIcons

apps/mobile/packages/features/staff/payments/lib/src/presentation/pages/payments_page.dart

@@ -47,7 +47,7 @@ class _PaymentsPageState extends State<PaymentsPage> {
             } else if (state is PaymentsError) {
               return Center(
                 child: Padding(
-                  padding: const EdgeInsets.all(16.0),
+                  padding: const EdgeInsets.all(UiConstants.space4),
                   child: Text(
                     translateErrorKey(state.message),
                     textAlign: TextAlign.center,
@@ -218,7 +218,7 @@ class _PaymentsPageState extends State<PaymentsPage> {
                       ],
                     ),
 
-                  const SizedBox(height: 100),
+                  const SizedBox(height: UiConstants.space24),
                 ],
               ),
             ),
@@ -236,7 +236,7 @@ class _PaymentsPageState extends State<PaymentsPage> {
         child: Container(
           padding: const EdgeInsets.symmetric(vertical: UiConstants.space2),
           decoration: BoxDecoration(
-            color: isSelected ? UiColors.white : Colors.transparent,
+            color: isSelected ? UiColors.white : UiColors.transparent,
             borderRadius: BorderRadius.circular(UiConstants.radiusMdValue),
           ),
           child: Center(