Re-translate the Japanese version (#1871)

* Retranslate Japanese docs with GPT-5.4

* Retranslate Japanese code with GPT-5.4

ja/codes/go/chapter_tree/binary_tree_dfs.go

@@ -0,0 +1,44 @@
+// File: binary_tree_dfs.go
+// Created Time: 2022-11-26
+// Author: Reanon (793584285@qq.com)
+
+package chapter_tree
+
+import (
+	. "github.com/krahets/hello-algo/pkg"
+)
+
+var nums []any
+
+/* 先行順走査 */
+func preOrder(node *TreeNode) {
+	if node == nil {
+		return
+	}
+	// 訪問順序：根ノード -> 左部分木 -> 右部分木
+	nums = append(nums, node.Val)
+	preOrder(node.Left)
+	preOrder(node.Right)
+}
+
+/* 中順走査 */
+func inOrder(node *TreeNode) {
+	if node == nil {
+		return
+	}
+	// 訪問優先順: 左部分木 -> 根ノード -> 右部分木
+	inOrder(node.Left)
+	nums = append(nums, node.Val)
+	inOrder(node.Right)
+}
+
+/* 後順走査 */
+func postOrder(node *TreeNode) {
+	if node == nil {
+		return
+	}
+	// 訪問優先順: 左部分木 -> 右部分木 -> 根ノード
+	postOrder(node.Left)
+	postOrder(node.Right)
+	nums = append(nums, node.Val)
+}