chore: new jsx transform

[yslpn]

Description

Switch React packages to the automatic JSX runtime: Babel/esbuild now emit JSX without explicit React imports, and the React tsconfig uses react-jsx. Raised the minimum supported react peer to 16.14.0 to align with the automatic runtime requirements. This follows the guidance in the new JSX transform announcement: https://legacy.reactjs.org/blog/2020/09/22/introducing-the-new-jsx-transform.html

• No more import React — you don't need to import React in every file that uses JSX
• Smaller bundle size — slightly reduces compiled output

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Examples update

Fixes # N/A

Checklist

• I have read the CONTRIBUTING and CODE_OF_CONDUCT docs
• I have added tests that prove my fix is effective or that my feature works
• I have added the necessary documentation (if appropriate)

[vercel]

@yslpn is attempting to deploy a commit to the Crowdin Team on Vercel.

A member of the Team first needs to authorize it.

[codecov]

Codecov Report

❌ Patch coverage is 93.75000% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 76.61%. Comparing base (6bb8983) to head (3bbfea1).
⚠️ Report is 243 commits behind head on main.

Files with missing lines	Patch %	Lines
packages/react/src/format.tsx	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2387      +/-   ##
==========================================
- Coverage   77.05%   76.61%   -0.44%     
==========================================
  Files          84      100      +16     
  Lines        2157     2745     +588     
  Branches      555      715     +160     
==========================================
+ Hits         1662     2103     +441     
- Misses        382      513     +131     
- Partials      113      129      +16     

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[vonovak]

technically speaking, this is a breaking change. Nothing wrong with that. But I say.. let's bump this to 18 and stop caring about the old versions

[yslpn]

I agree with you. If we upgraded React, we could use useSyncExternalStore to sync react state with i18n state. It's a simpler and more performant option than using useEffect.

But I need other contributors' agreement that we're ready to upgrade React to version 18.

[yslpn]

@andrii-bodnar @timofei-iatsenko

What do you think about raising the React version to 18?