feat: add metadata validation and scan acceptance support

src/main/java/com/music/metadata/service/ScanFileProcessor.java

@@ -0,0 +1,9 @@
+package com.music.metadata.service;
+
+import com.music.metadata.domain.scan.ScanProcessingOutcome;
+import com.music.metadata.infrastructure.entity.ScanItemEntity;
+
+public interface ScanFileProcessor {
+
+    ScanProcessingOutcome process(Long taskId, ScanItemEntity scanItemEntity);
+}