fix: Recent Transactions widget ignored the selected dashboard month

RecentTransactionsCard queried transactions without year/month filters,
so it always showed the latest 6 transactions globally instead of the
ones for the month picked in the MonthSelector. DashboardPage now
passes its year/month state down to the card, which forwards it to
useTransactions.

frontend/src/pages/DashboardPage.tsx

@@ -69,7 +69,7 @@ export function DashboardPage() {
 
       <div className="grid grid-cols-1 gap-4 lg:grid-cols-[1.4fr_1fr]">
         <SpendingByCategoryCard items={data?.spending_by_category ?? []} />
-        <RecentTransactionsCard />
+        <RecentTransactionsCard year={year} month={month} />
       </div>
     </div>
   );