Fix CLI split diff lhs not getting a language registered (#60914)

Closes https://github.com/zed-industries/zed/issues/60751

Release Notes:

- Fixed split file diff missing syntax highlighting
4884a7b46eKirill Bulatov committed on 7/13/2026, 5:55:34 PM· committed by GitHubparentc399451
1 file changedLine totals unavailable