Context:
今日{きょう}の夕食{ゆうしょく}は私{わたし}がごちそうします。
I've research on ご馳走{ちそう}, from the etymology to popular usages, but I'm still unsure whether it would be used, in this phrase, to invite someone to dinner somewhere or to indicate that "I" would be the one doing the dinner tonight.
If it is a invite, is it an invitation to eat in a restaurant or somewhere outside, or is it that "I" am inviting (someone) to eating at my house?