Add Belarusian language support, using the historic white-red-white flag instead of the Lukashenko regime’s flag

Belarusian is not currently available as a Fluxer interface language, preventing Belarusian-speaking users from using the app in their native language. It is also important to represent Belarusian correctly, using its historic national white-red-white flag rather than the state flag used by the Lukashenko regime.

Add full Belarusian (Беларуская мова) interface translation across all supported platforms. Use the historic white-red-white Belarusian flag as the language icon wherever language flags are displayed, instead of the current state flag.

The attached image shows the exact historic Belarusian white-red-white flag I would like to see used as the language icon. This flag represents Belarusian national identity and should be used instead of the current state flag associated with Lukashenko's regime.