perf: otimizar dashboard com indexes, cache e consolidação de queries (v1.3.0)

- Adicionar indexes compostos em lancamentos para queries frequentes
- Eliminar ~20 JOINs com pagadores via helper cacheado getAdminPagadorId()
- Consolidar queries: income-expense-balance (12→1), payment-status (2→1), categories (4→2)
- Adicionar cache cross-request via unstable_cache com tag-based invalidation
- Limitar scan de métricas a 24 meses
- Deduplicar auth session por request via React.cache()

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

components/month-picker/month-navigation.tsx

@@ -89,7 +89,7 @@ export default function MonthNavigation() {
 
 				<div className="flex items-center">
 					<div
-						className="mx-1 space-x-1 capitalize font-bold"
+						className="mx-1 space-x-1 capitalize font-semibold"
 						aria-current={!isDifferentFromCurrent ? "date" : undefined}
 						aria-label={`Período selecionado: ${currentMonthLabel} de ${currentYear}`}
 					>