Preserve stray test.rs scratch file from working tree

[rorychatt]

SyncRepo found a staged, uncommitted test.rs at the repo root on main and preserved it here rather than discarding it. Opened for review so the work is not lost — this is very likely a leftover scratch file that should simply be deleted instead of merged.

What was in the working tree

A single staged file, test.rs, containing an empty main:

fn  main ( ) {
}

It sits at the repo root, outside every crate in the workspace (rusty, rusty-server, rusty-macros, rusty-docs, src), so nothing builds or references it.

Notes for the reviewer

• The staged file disappeared from the working tree mid-sync (a concurrent process removed it). It was recovered byte-for-byte from the still-reachable git blob 2420578, so no content was lost.
• The repo's pre-commit hook ran rustfmt over the staged file, so the committed content is the reformatted fn main() {} rather than the original odd spacing shown above.

Suggested action

Close this PR and delete the branch, unless someone recognizes test.rs as intentional.