Add chunked transfer encoding support for LFS uploads (#36380)

Enable chunked transfer encoding for Git LFS uploads by adding
Transfer-Encoding: chunked header to upload action responses. This
prevents large file uploads (100+ MB) from being blocked by reverse
proxies like Cloudflare that buffer non-chunked requests.

Fix https://github.com/go-gitea/gitea/issues/22233

---------

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

tests/integration/api_repo_lfs_test.go

@@ -317,6 +317,7 @@ func TestAPILFSBatch(t *testing.T) {
 			ul := br.Objects[0].Actions["upload"]
 			assert.NotNil(t, ul)
 			assert.NotEmpty(t, ul.Href)
+			assert.Equal(t, "chunked", ul.Header["Transfer-Encoding"], "git-lfs client needs Transfer-Encoding to do chunked transfer")
 			assert.Contains(t, br.Objects[0].Actions, "verify")
 			vl := br.Objects[0].Actions["verify"]
 			assert.NotNil(t, vl)