docs: add Ask AI feature

[mateuszlampert]

Description

• bumped docusaurus, react, node and t-rex-ui versions for our docs
• added Docsearch Ask AI feature to our docs
• configured Algolia Ask AI assistant
• updated docs-build-check workflow to use required node version (20+)

Introduces a breaking change?

• Yes
• No

Type of change

• Bug fix (change which fixes an issue)
• New feature (change which adds functionality)
• Documentation update (improves or adds clarity to existing documentation)
• Other (chores, tests, code style improvements etc.)

Tested on

• iOS
• Android

Testing instructions

• try to build docs locally (yarn build -> yarn serve) from this branch

Screenshots

Screen.Recording.2026-01-22.at.10.41.43.mov

Screen.Recording.2026-01-22.at.10.43.53.mov

Related issues

Checklist

• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have updated the documentation accordingly
• My changes generate no new warnings

Additional notes

[msluszniak]

I guess to support this feature, we need to bump node.js version, see docs CI:

[msluszniak]

🚀