Добавлен Hybernate и реализован прототип БД

src/main/java/com/rosetta/im/database/converters/StringListConverter.java

@@ -0,0 +1,27 @@
+package com.rosetta.im.database.converters;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+import jakarta.persistence.AttributeConverter;
+import jakarta.persistence.Converter;
+
+@Converter
+public class StringListConverter implements AttributeConverter<List<String>, String> {
+    @Override
+    public String convertToDatabaseColumn(List<String> attribute) {
+        if (attribute == null || attribute.isEmpty()) {
+            return "";
+        }
+        return String.join(",", attribute);
+    }
+
+    @Override
+    public List<String> convertToEntityAttribute(String dbData) {
+        if (dbData == null || dbData.isBlank()) {
+            return new ArrayList<>();
+        }
+        return new ArrayList<>(Arrays.asList(dbData.split(",")));
+    }
+}