feat: i18n support

[nekomeowww]

• i18n help messages
• i18n error message handling
• i18n reply message handling
• i18n prompt with multi-language support
  • chore: translate recap prompt to English #70
• configurable i18n options (through inline keyboard or whatever)

[OverflowCat]

An i18n library is necessary to manipulate locale strings with ease. Which one would you recommend?

[nekomeowww]

An i18n library is necessary to manipulate locale strings with ease. Which one would you recommend?

I used to use github.com/nicksnyder/go-i18n