Koa i18n Middleware

koa-i18n is a lightweight internationalization (i18n) middleware for Koa applications, built upon the `i18n-2` library. The current stable version, 2.1.0, is designed for Koa 2.x, while a separate 1.x branch targets Koa 1.x applications. Release cadence appears to be tied to Koa's major versions, with `2.x` being the current 'next' major iteration as of its release 9 years ago. A key differentiator is its reliance on `koa-locale` for robust locale detection, supporting various strategies including query parameters, subdomains, cookies, HTTP headers (`Accept-Language`), URL segments, and top-level domains (TLD), with the flexibility to add custom detection functions. This allows developers to tailor how the application determines the user's preferred language, making it suitable for multi-lingual web services. It provides a simple API through `ctx.i18n.__()` for translating keys.