Lingui expects the codes to be compliant to BCP-47 while weblate was not set up to create the resource files in that format.
And react-i18next was able to just handle them.
fixes#1058
Switch to "lingui" for better DX.
Tried to persist existing languages as much as possible.
Removed "vite-plugin-node-polyfills" because it's incompatible with "lingui"
