refactor: update spacing in Find, History, and My Shifts tabs for consistency

apps/mobile/packages/features/staff/shifts/lib/src/presentation/pages/shifts_page.dart

@@ -130,6 +130,8 @@ class _ShiftsPageState extends State<ShiftsPage> {
                           historyShifts,
                         ),
                 ),
+
+                
               ],
             ),
           );

apps/mobile/packages/features/staff/shifts/lib/src/presentation/widgets/tabs/find_shifts_tab.dart

@@ -175,7 +175,7 @@ class _FindShiftsTabState extends State<FindShiftsTab> {
                           ),
                         ),
                       ),
-                      const SizedBox(height: 40),
+                      const SizedBox(height: UiConstants.space32),
                     ],
                   ),
                 ),

apps/mobile/packages/features/staff/shifts/lib/src/presentation/widgets/tabs/history_shifts_tab.dart

@@ -40,7 +40,7 @@ class HistoryShiftsTab extends StatelessWidget {
               ),
             ),
           ),
-          const SizedBox(height: 40),
+          const SizedBox(height: UiConstants.space32),
         ],
       ),
     );

apps/mobile/packages/features/staff/shifts/lib/src/presentation/widgets/tabs/my_shifts_tab.dart

@@ -353,7 +353,7 @@ class _MyShiftsTabState extends State<MyShiftsTab> {
                     subtitle: "Try finding new jobs in the Find tab",
                   ),
                 
-                 const SizedBox(height: 40),
+                 const SizedBox(height: UiConstants.space32),
               ],
             ),
           ),