Attach files that aren't images to threads.

[mimen]

Sometimes I just want to attach a reference file, a folder, or something, and I just get an error. Claude Code has perfectly fine behavior for those, which is to just paste the filename with the full cwd, so the agent can at least figure out the file I'm trying to attach and do whatever it wants with it.

Love the special handling for images, but all files really should be able to be attached.