The feishu channel was not passing mediaLocalRoots when calling
sendMediaFeishu, causing loadWebMedia to reject local file paths
due to security restrictions. This meant agent-generated media
(like images from image_generate tool) would fail to upload and
fall back to sending the local path as text.
Now properly passes agent-scoped media roots (workspace, tmp, etc.)
to allow reading and uploading local media files to Feishu.
9cf0e16925