feat: upgrade vite to v8.0.0-beta.8 (Rolldown-powered) (#8127)

## Summary

Upgrades Vite from v7.3.0 to v8.0.0-beta.8, which uses Rolldown
(Rust-based bundler) instead of Rollup.

## Changes

- Updated `vite` to `^8.0.0-beta.8` in pnpm-workspace.yaml catalog
- Added pnpm overrides to ensure all dependencies (including vitest) use
Vite 8

## Notes

- Vite 8 is still in **beta** - no stable release yet
- Uses [Rolldown](https://rolldown.rs/) instead of Rollup for production
builds
- Build, typecheck, and lint all pass
- Per the [Vite 8 migration
guide](https://vite.dev/blog/announcing-vite8-beta), pnpm overrides are
required for tools like Vitest that bundle their own Vite types

## Testing

- [x] `pnpm typecheck` passes
- [x] `pnpm build` succeeds (~13s build time)
- [x] `pnpm lint` passes

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-8127-feat-upgrade-vite-to-v8-0-0-beta-8-Rolldown-powered-2eb6d73d365081e3bdb6f500e140eb88)
by [Unito](https://www.unito.io)

Co-authored-by: Amp <amp@ampcode.com>

pnpm-workspace.yaml

@@ -93,7 +93,7 @@ catalog:
   unplugin-icons: ^22.5.0
   unplugin-typegpu: 0.8.0
   unplugin-vue-components: ^30.0.0
-  vite: ^7.3.0
+  vite: ^8.0.0-beta.8
   vite-plugin-dts: ^4.5.4
   vite-plugin-html: ^3.2.2
   vite-plugin-vue-devtools: ^8.0.0