Fix i18n in webapp and get rid of quotes Django app

So long quotes, you were funny while you lasted 🫡

Also fixes i18n loading and use json5 instead of just jsonc; vue-i18n & tooling doesn't look for jsonc files (only json and json5), so instead of patching the deps left and right let's just go for json5 🤷

I'm quite bothered by keys being sometimes quoted due to the presence of a dash though... Maybe tweaking the lint config is an option or use underscores instead