[ADD] Categoryのビジネスロジック作成のためのサービスクラスを作成しました。

src/main/java/com/example/demo/app/domain/service/CategoryService.java

@@ -0,0 +1,10 @@
+package com.example.demo.app.domain.service;
+
+import java.util.List;
+
+import com.example.demo.app.domain.model.CategoryModel;
+
+public interface CategoryService {
+
+	public List<CategoryModel> findAll();
+}

src/main/java/com/example/demo/app/domain/service/impl/CategoryServiceImpl.java

@@ -0,0 +1,25 @@
+package com.example.demo.app.domain.service.impl;
+
+import java.util.List;
+
+import org.springframework.stereotype.Service;
+
+import com.example.demo.app.domain.model.CategoryModel;
+import com.example.demo.app.domain.service.CategoryService;
+import com.example.demo.app.infra.repository.CategoryRepository;
+
+import lombok.RequiredArgsConstructor;
+
+@Service
+@RequiredArgsConstructor
+public class CategoryServiceImpl implements CategoryService{
+
+	private final CategoryRepository categoryRepository;
+	
+	public List<CategoryModel> findAll() {
+		
+		return CategoryModel.convertFrom(categoryRepository.findAll());
+		
+	}
+	
+}