Spanish translations

[serivt]

Summary

This PR introduces initial support for Spanish localization. It includes the setup for the new language and a translation of the Get Started / Introduction section into Spanish.

What’s included

• Configuration scaffolding for Spanish language support.
• Full Spanish translation of the "Get Started / Introduction" section.
• Minor adjustments to navigation to include Spanish under language selector.

Next steps

This is an initial partial translation. Remaining sections will follow in subsequent PRs.

Checklist

• Delete items not relevant to your PR
• URL changes should add a redirect to the old URL via https://github.com/ClickHouse/clickhouse-docs/blob/main/docusaurus.config.js
• If adding a new integration page, also add an entry to the integrations list here: https://github.com/ClickHouse/clickhouse-docs/blob/main/docs/integrations/index.mdx

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[Blargian]

Hi @serivt, I'm really excited to see this PR, thank you so much! We've had some internal discussions about adding Spanish as a supported language, so I am taking this as the sign it's time to do it.

We're using an LLM to generate our translations from English so what I will do is open a PR with the complete documentation generated with an LLM and then we can merge in your PR to replace the LLM getting started section with yours.

One thing that is extremely helpful is having a native speaker translate some technical terms manually before we run the translations. These are terms which can be mistranslated by the LLM. Would you be interested in assisting with this? The list of terms is here. I've gone ahead and added a column for Spanish with translations from Google Gemini, but it will be nice for a native speaker to confirm the accuracy: https://github.com/ClickHouse/clickhouse-docs/blob/main/scripts/translate/glossary.csv

If a term doesn't have a good natural sounding translation, it's okay to leave the translation as the English word.

[serivt]

Hi @Blargian, glad to help out! I’ll take a look at the glossary and see what I can do.