Fix welcome message and sync

- Prevent duplicate welcome messages.
- Remove sync notifications.
- Ensure automatic sync updates last sync time.

src/components/sync/SyncStatus.tsx

@@ -1,8 +1,9 @@
 
-import React from 'react';
+import React, { useEffect } from 'react';
 import { RefreshCw } from "lucide-react";
 import { Button } from "@/components/ui/button";
 import { useNavigate } from "react-router-dom";
+import useNotifications from '@/hooks/useNotifications';
 
 interface SyncStatusProps {
   enabled: boolean;
@@ -20,6 +21,18 @@ const SyncStatus: React.FC<SyncStatusProps> = ({
   onManualSync
 }) => {
   const navigate = useNavigate();
+  const { addNotification } = useNotifications();
+
+  // 동기화 버튼 클릭 시 알림 추가
+  const handleSyncClick = async () => {
+    if (syncing) return;
+    
+    try {
+      await onManualSync();
+    } catch (error) {
+      console.error('수동 동기화 실패:', error);
+    }
+  };
 
   if (!enabled) return null;
 
@@ -29,7 +42,7 @@ const SyncStatus: React.FC<SyncStatusProps> = ({
         <div className="flex justify-between items-center text-sm">
           <span className="text-muted-foreground">마지막 동기화: {lastSync}</span>
           <button 
-            onClick={onManualSync}
+            onClick={handleSyncClick}
             disabled={syncing}
             className="neuro-button py-1 px-3 flex items-center gap-1 bg-neuro-income text-white hover:bg-neuro-income/90"
           >