feat(frontend): add API client, layout, and routing

- Create Axios-based API client with sources, jobs, and dashboard endpoints
- Add responsive Layout component with navigation sidebar
- Set up React Router with Dashboard, Backups, and Settings routes
- Configure TanStack Query provider with default options
- Use lucide-react for navigation icons

frontend/node_modules/d3-time-format/locale/ko-KR.json

@@ -0,0 +1,10 @@
+{
+  "dateTime": "%Y/%m/%d %a %X",
+  "date": "%Y/%m/%d",
+  "time": "%H:%M:%S",
+  "periods": ["오전", "오후"],
+  "days": ["일요일", "월요일", "화요일", "수요일", "목요일", "금요일", "토요일"],
+  "shortDays": ["일", "월", "화", "수", "목", "금", "토"],
+  "months": ["1월", "2월", "3월", "4월", "5월", "6월", "7월", "8월", "9월", "10월", "11월", "12월"],
+  "shortMonths": ["1월", "2월", "3월", "4월", "5월", "6월", "7월", "8월", "9월", "10월", "11월", "12월"]
+}