📝 Docs: dateFormat 추가

src/utils/dateFormat.ts

@@ -0,0 +1,12 @@
+export const dateToString = (date: Date): string => {
+  const year = date.getFullYear()
+  const month = String(date.getMonth() + 1).padStart(2, '0')
+  const day = String(date.getDate()).padStart(2, '0')
+
+  return `${year}-${month}-${day}`
+}
+
+export const stringToDate = (dateString: string): Date => {
+  const [year, month, day] = dateString.split('-').map(Number)
+  return new Date(year, month - 1, day)
+}