feat: Add spacing between invoice history and spending breakdown card in billing view

apps/mobile/packages/features/client/billing/lib/src/presentation/pages/billing_page.dart

@@ -200,6 +200,8 @@ class _BillingViewState extends State<BillingView> {
           const SpendingBreakdownCard(),
           if (state.invoiceHistory.isEmpty) _buildEmptyState(context)
           else InvoiceHistorySection(invoices: state.invoiceHistory),
+
+          const SizedBox(height: UiConstants.space32),
         ],
       ),
     );