refactor: update CoveragePage layout to use fixed height for shift list spacing

apps/mobile/packages/features/client/client_coverage/lib/src/presentation/pages/coverage_page.dart

@@ -285,7 +285,9 @@ class _CoveragePageState extends State<CoveragePage> {
           ),
           const SizedBox(height: UiConstants.space3),
           CoverageShiftList(shifts: state.shifts),
-          SizedBox(height: MediaQuery.of(context).size.height * 0.8),
+          const SizedBox(
+            height: UiConstants.space24,
+          ),
         ],
       ),
     );