feat(admin-content): 관리자 콘텐츠 개별 정산 요율 수정을 지원한다

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

src/main/kotlin/kr/co/vividnext/sodalive/content/AudioContent.kt

@@ -35,6 +35,7 @@ data class AudioContent(
     var languageCode: String?,
     var playCount: Long = 0,
     var price: Int = 0,
+    var settlementRatio: Int? = null,
     var releaseDate: LocalDateTime? = null,
     val limited: Int? = null,
     var remaining: Int? = null,