Two more .nitro entry points in the main import path still wrote the
supplied buffer verbatim: an attached `providedNitro` and a bundle pulled
back by `resolveMissingNitro`. Both are real furniture imports, so they
could still land a PNG texture while the SWF, clone and upload paths
produced WebP.
Route both through the same normalisation, falling back to the original
bytes with a warning if the texture cannot be decoded.