fix(api): commit tree SHA is the commit ID (#39449)

Fixes #39448

modules/git/commit_convert_gogit.go

@@ -66,6 +66,7 @@ func convertPGPSignature(c *object.Commit) *CommitSignature {
 func convertCommit(c *object.Commit) *Commit {
 	return &Commit{
 		ID:            ParseGogitHash(c.Hash),
+		TreeID:        ParseGogitHash(c.TreeHash),
 		CommitMessage: CommitMessage{MessageRaw: c.Message},
 		Committer:     &c.Committer,
 		Author:        &c.Author,

modules/git/notes_test.go

@@ -37,6 +37,7 @@ func TestGetNoteNestedWithCache(t *testing.T) {
 	assert.Equal(t, "Note 1", note.BlobMessage.MessageUTF8())
 	assert.Equal(t, "ba0a96fa63532d6c5087ecef070b0250ed72fa47", note.TreePath)
 	assert.Equal(t, "Filip Navara", lastCommit.Author.Name)
+	assert.Equal(t, "fec9fe57e9864fe537f02f825e377c4a8a65ad2e", lastCommit.TreeID.String())
 
 	note, lastCommit, err = GetNoteWithLastCommit(t.Context(), repo, "3e668dbfac39cbc80a9ff9c61eb565d944453ba4")
 	assert.NoError(t, err)