feat: add commit treeId() method

docs/ko/reference/Commit/Methods/treeId.md

@@ -0,0 +1,23 @@
+# treeId
+
+이 커밋이 가리키는 트리의 ID를 가져와요.
+
+ODB에서 Git 개체를 가져오기 위한 시도는 하지 않아요.
+
+## 시그니처
+
+```ts
+class Commit {
+  treeId(): string;
+}
+```
+
+### 반환 값
+
+<ul class="param-ul">
+  <li class="param-li param-li-root">
+    <span class="param-type">string</span>
+    <br>
+    <p class="param-description">커밋이 가리키는 트리의 ID 값</p>
+  </li>
+</ul>

docs/reference/Commit/Methods/treeId.md

@@ -0,0 +1,23 @@
+# treeId
+
+Get the id of the tree pointed to by this commit.
+
+No attempts are made to fetch an object from the ODB.
+
+## Signature
+
+```ts
+class Commit {
+  treeId(): string;
+}
+```
+
+### Returns
+
+<ul class="param-ul">
+  <li class="param-li param-li-root">
+    <span class="param-type">string</span>
+    <br>
+    <p class="param-description">Get the id of the tree pointed to by a commit.</p>
+  </li>
+</ul>

src/commit.rs

@@ -227,6 +227,25 @@ impl Commit {
     Ok(time)
   }
 
+  #[napi]
+  /// Get the id of the tree pointed to by this commit.
+  ///
+  /// No attempts are made to fetch an object from the ODB.
+  ///
+  /// @category Commit/Methods
+  ///
+  /// @signature
+  /// ```ts
+  /// class Commit {
+  ///   treeId(): string;
+  /// }
+  /// ```
+  ///
+  /// @returns Get the id of the tree pointed to by a commit.
+  pub fn tree_id(&self) -> String {
+    self.inner.tree_id().to_string()
+  }
+
   #[napi]
   /// Get the tree pointed to by a commit.
   ///