[Bug]: Apps launched from Gamehub switch to Farsi due to LANGUAGE env fallback

[nooob-developer]

What happened?

When launching Lutris, Bottles, or Steam through Gamehub, their UI switches
to Farsi unexpectedly. Launching the same apps from a terminal or app menu
keeps them in English. Root cause: Gamehub passes the LANGUAGE env variable
(e.g. en_US:fa) straight through to spawned child processes without
sanitizing it, and gettext falls back to the fa entry since there's no
English .mo catalog.

Reproduction steps

1. Set LANGUAGE=en_US:fa in your session (common bilingual setup).
2. Open Gamehub, launch Lutris or Bottles from the launcher list.
3. Observe the app's UI appears in Farsi instead of English.
4. Launch the same app from terminal or app menu it stays in English.

Parch Linux version

ArchLinux rolling

Affected area

Core applications

Relevant log output

Confirmation

• I searched existing issues and did not find a duplicate.
• I agree to follow this project's Code of Conduct.