feat(dashboard): add missing receivables stat card to DashboardPage

src/pages/dashboard/DashboardPage.vue

@@ -92,6 +92,12 @@
           :value="formatToBRLCurrency(unitsSummary.revenue)"
           :subtitle="revenuePeriodLabel"
         />
+        <DashboardStatCard
+          title="Recebíveis Faltantes"
+          icon="mdi-cash-clock"
+          :value="formatToBRLCurrency(unitsSummary.missing_receivables)"
+          :subtitle="receivablesPeriodLabel"
+        />
         <DashboardStatCard
           title="Contratos das Unidades"
           icon="mdi-file-document-check-outline"
@@ -247,6 +253,7 @@ const generalRevenue   = ref({ value: 0, pending_count: 0 });
 const unitsSummary     = ref({
   total: 0,
   revenue: 0,
+  missing_receivables: 0,
   active_contracts: 0,
   without_active_contract: 0,
 });
@@ -309,6 +316,10 @@ const revenuePeriodLabel = computed(() => {
   return `De ${format(revenuePeriod.value.startDate)} a ${format(revenuePeriod.value.endDate)}`;
 });
 
+const receivablesPeriodLabel = computed(() =>
+  revenuePeriodLabel.value.replace("Faturamento em", "Vencimento em"),
+);
+
 /**
  * Array of unit IDs to use as filter.
  * - Group selected  → all unit IDs in that group