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

apps/mobile/packages/features/staff/home/lib/src/presentation/widgets/shift_card.dart

@@ -206,7 +206,7 @@ class _ShiftCardState extends State<ShiftCard> {
                             )
                           : Icon(
                               UiIcons.building,
-                              size: 28,
+                              size: UiConstants.iconXl - 4, // 28px
                               color: UiColors.primary,
                             ),
                     ),
@@ -269,7 +269,7 @@ class _ShiftCardState extends State<ShiftCard> {
                   children: [
                     Icon(
                       UiIcons.mapPin,
-                      size: 16,
+                      size: UiConstants.iconSm,
                       color: UiColors.mutedForeground,
                     ),
                     const SizedBox(width: 6),
@@ -283,7 +283,7 @@ class _ShiftCardState extends State<ShiftCard> {
                     const SizedBox(width: UiConstants.space4),
                     Icon(
                       UiIcons.calendar,
-                      size: 16,
+                      size: UiConstants.iconSm,
                       color: UiColors.mutedForeground,
                     ),
                     const SizedBox(width: 6),
@@ -383,8 +383,8 @@ class _ShiftCardState extends State<ShiftCard> {
       child: Row(
         mainAxisSize: MainAxisSize.min,
         children: [
-          Icon(icon, size: 14, color: text),
-          const SizedBox(width: 4),
+          Icon(icon, size: UiConstants.iconSm - 2, color: text),
+          const SizedBox(width: UiConstants.space1),
           Flexible(
             child: Text(
               label,