Fix onboarding and data issues

- Fix issue where welcome dialog reappears.
- Fix issue where new expenses are not reflected.
- Improve card layout on mobile devices.

src/components/onboarding/WelcomeDialog.tsx

@@ -22,6 +22,10 @@ const WelcomeDialog: React.FC<WelcomeDialogProps> = ({ open, onClose }) => {
   const [dontShowAgain, setDontShowAgain] = useState(false);
 
   const handleClose = () => {
+    // 체크박스가 체크되어 있으면 localStorage에 직접 저장
+    if (dontShowAgain) {
+      localStorage.setItem('dontShowWelcome', 'true');
+    }
     onClose(dontShowAgain);
   };