Update Vite to version 8

[kmcginnes]

Description

Migrate from Vite 7 to Vite 8, which replaces esbuild + Rollup with Rolldown + Oxc for bundling, transforms, and minification.

Dependency changes

• vite ^7.3.1 → ^8.0.0
• @vitejs/plugin-react ^5.1.4 → ^6.0.0 (drops built-in Babel)
• @tailwindcss/vite ^4.2.1 → ^4.2.2 (Vite 8 peer dep)
• babel-plugin-react-compiler 19.1.0-rc.3 → ^1.0.0 (stable release)
• vitest / @vitest/coverage-v8 4.0.18 → 4.1.2 (Vite 8 peer dep)
• Add @rolldown/plugin-babel 0.2.2 (React Compiler now requires a separate Babel plugin)
• Remove vite-tsconfig-paths (Vite 8 supports tsconfig paths natively)

Config changes

• Replace vite-tsconfig-paths plugin with resolve: { tsconfigPaths: true }
• Move React Compiler to separate @rolldown/plugin-babel with reactCompilerPreset(), since @vitejs/plugin-react v6 removed built-in Babel support
• Remove unnecessary /// <reference types="vitest" /> directive

Build comparison

Metric	Vite 7	Vite 8	Change
Build time (vite)	12.73s	5.07s	-60%
JS chunks	2	3	Better splitting
Total JS (gzip)	970 KB	922 KB	-5.0%
CSS (gzip)	12.8 KB	12.8 KB	~unchanged

Note: The build emits a timing warning for @rolldown/plugin-babel since the React Compiler does non-trivial transforms. This is expected.

Migration guide

https://vite.dev/guide/migration

Validation

• All 1562 tests pass across 145 test files
• No type errors, lint errors, or format issues
• Production build succeeds with smaller output
• Audited every item in the Vite 8 migration guide against this codebase

Related Issues

• Resolves Update Vite to version 8 #1647

Check List

• I confirm that my contribution is made under the terms of the Apache 2.0 license.
• I have verified pnpm checks passes with no errors.
• I have verified pnpm test passes with no failures.
• I have covered new added functionality with unit tests if necessary.
• I have updated documentation if necessary.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 72.56%. Comparing base (c5affc5) to head (68b6428).
⚠️ Report is 123 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #1651       +/-   ##
===========================================
+ Coverage   47.81%   72.56%   +24.75%     
===========================================
  Files         382      408       +26     
  Lines        8525    12265     +3740     
  Branches     3159     3518      +359     
===========================================
+ Hits         4076     8900     +4824     
+ Misses       3070     2345      -725     
+ Partials     1379     1020      -359     

Flag	Coverage Δ
unittests	72.56% <ø> (+24.75%)	⬆️

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