[Playground] Is upstream open to i18n support for Cube Playground? #11992

Hi team, and thanks for the great work on Cube.

We use Cube as the semantic layer in an internal analytics platform, and our
team members work primarily in Chinese. The Playground (dev console at :4000)
is the main interface our non-English-speaking developers and analysts interact
with when building data models and debugging queries.

Before writing any code, we'd like to ask: would the maintainers be open to
adding i18n support to the Playground?

Concretely, we'd envision:

1. Introducing a lightweight i18n layer (e.g. react-i18next) in
   packages/cubejs-playground
2. Extracting hardcoded UI strings into locale files (en, zh-CN to start)
3. A language toggle persisted in localStorage, defaulting to English —
   zero behavior change for existing users

We understand the Playground is a dev tool and English-only is fine for most
users, so we don't want to invest in a large PR that has no chance of being
merged. If upstream is open to it, we're happy to do the extraction work and
maintain the zh-CN locale long-term. If not, we'll keep a local fork/patch.

Would love to hear your thoughts. Thanks!