attachImagePath fetched its thumbnail through readDesktopFileDataUrl, which in
remote mode routes every read to the gateway fs bridge. Paperclip picks,
clipboard saves, and OS drops always produce paths on the LOCAL machine, so the
gateway read 404s — toasting "image preview failed" and dropping the thumbnail
even though the attach itself works (upload reads local bytes via the Electron
bridge). Read the local bridge first and fall back to the remote facade, which
still serves in-app drags from the remote project tree. Local mode is
unchanged (the facade already reads locally there).
Follow-up to #56572, which restored the remote paperclip picker and made this
path reachable from the picker as well.
fe82b3a774