feat(content-ranking): 랭킹 공개 시각 정책을 추가한다

src/main/kotlin/kr/co/vividnext/sodalive/v2/ranking/domain/CreatorRankingPeriodPolicy.kt

@@ -25,7 +25,15 @@ class CreatorRankingPeriodPolicy {
         )
     }
 
+    fun resolveVisibleFromAtUtc(aggregationEndAtKst: LocalDateTime): LocalDateTime {
+        return aggregationEndAtKst.plusHours(VISIBLE_DELAY_HOURS)
+            .atZone(KST_ZONE)
+            .withZoneSameInstant(UTC_ZONE)
+            .toLocalDateTime()
+    }
+
     companion object {
+        private const val VISIBLE_DELAY_HOURS = 9L
         private val KST_ZONE: ZoneId = ZoneId.of("Asia/Seoul")
         private val UTC_ZONE: ZoneId = ZoneId.of("UTC")
     }

src/main/kotlin/kr/co/vividnext/sodalive/v2/ranking/domain/CreatorRankingType.kt

@@ -0,0 +1,5 @@
+package kr.co.vividnext.sodalive.v2.ranking.domain
+
+enum class CreatorRankingType {
+    WEEKLY
+}

src/test/kotlin/kr/co/vividnext/sodalive/v2/ranking/domain/CreatorRankingPeriodPolicyTest.kt

@@ -56,4 +56,14 @@ class CreatorRankingPeriodPolicyTest {
         assertEquals(LocalDateTime.of(2026, 5, 31, 15, 0), utcRange.startInclusiveUtc)
         assertEquals(LocalDateTime.of(2026, 6, 7, 15, 0), utcRange.endExclusiveUtc)
     }
+
+    @Test
+    @DisplayName("집계 종료일 월요일 09시 KST를 공개 노출 UTC 시각으로 변환한다")
+    fun shouldResolveVisibleFromAtUtcByAggregationEndAtKst() {
+        val aggregationEndAtKst = LocalDateTime.of(2026, 6, 8, 0, 0)
+
+        val visibleFromAtUtc = policy.resolveVisibleFromAtUtc(aggregationEndAtKst)
+
+        assertEquals(LocalDateTime.of(2026, 6, 8, 0, 0), visibleFromAtUtc)
+    }
 }