Copilot panel fails on remote scp files

[Arakade]

Reproduction

Edit a remote file using vim scp://user@myserver[:port]//path/to/file.txt syntax.
Attempting to open the Copilot panel.

Error

Result is Lua exception E95 "Buffer with this name already exists".

Cause and workaround / fix

Looks like lua/copilot/panel.lua panel_uri_from_doc_uri() assumes doc URL starts file://. Switching ^file:// to ^%a+:// seems to fix it (but I don't know other implications like are other URL schemes explicitly supposed to fail?)