[FEATURE]#75 : LocalDateTime으로 일자 계산 로직 구현

core/common/src/main/kotlin/com/bff/wespot/common/util/DateTimeConverter.kt

@@ -1,6 +1,7 @@
 package com.bff.wespot.common.util
 
 import java.time.LocalDate
+import java.time.LocalDateTime
 import java.time.format.DateTimeFormatter
 import java.time.temporal.ChronoUnit
 
@@ -19,6 +20,17 @@ fun String.timeDifference(): Long {
     return daysDifference
 }
 
+fun LocalDateTime.toDateString(): String {
+    val currentDateTime = LocalDateTime.now()
+    val daysBetween = ChronoUnit.DAYS.between(this, currentDateTime)
+
+    return when (daysBetween) {
+        0L -> "오늘"
+        in 1..7 -> "${daysBetween}일 전"
+        else -> this.format(DateTimeFormatter.ofPattern("yyyy.MM.dd"))
+    }
+}
+
 fun Long.toDateString(date: String): String =
     when(this) {
         0L -> {