Revert Vite 8 / Rolldown upgrade

[pomfrida]

Background

We upgraded Vite 7 → 8 (which swaps the bundler from Rollup to Rolldown) in #4759 and #4762. Since then we've hit recurring regressions that have been costly to chase down:

• light-dark() expansion changed in built tokens. Rolldown/Lightning CSS handles light-dark() differently, which forced us to emit explicit dark-scope rules instead (fix: emit explicit dark-scope rules instead of light-dark() in tokens #4864 / e519ff2).
• Figma token sync is broken. eds-tokens-sync no longer works after the Rolldown migration, currently blocking 5xl letter spacing for UI typography is incorrect #4876.
• More regressions are likely — the bundler swap touches every build output.

Vite 8 + Rolldown is still very new for our use cases. Rather than keep firefighting downstream, revert to Vite 7 / Rollup. The next attempt is tracked separately.

Revert scope

PRs to revert:

• chore(deps): bump vite from 7.3.2 to 8.0.3 #4759 — vite 7.3.1 → 8.0.3 (the major)
• chore(deps): bump vite from 8.0.3 to 8.0.5 #4775 — vite 8.0.3 → 8.0.5
• chore(deps): bump @vitejs/plugin-react from 5.2.0 to 6.0.1 #4820 — @vitejs/plugin-react 5.2.0 → 6.0.1 (v6 likely requires Vite 8)
• chore(config): rename rollupOptions to rolldownOptions for Vite 8 #4762 — rollupOptions → rolldownOptions rename in 4 vite configs

Subsequent grouped Dependabot bumps that nudged vite up to ^8.0.9 need to have the vite line partially reverted; the rest of those groups can stay.

Affected files:

• packages/eds-tailwind/package.json
• packages/eds-tokens-build/{package.json, vite.config.ts}
• packages/eds-tokens-sync/{package.json, vite.config.ts}
• packages/eds-tokens/{package.json, vite.generate-variables.config.ts}
• packages/eds-utils/package.json
• apps/eds-color-palette-generator/{package.json, vite.config.ts}
• pnpm-lock.yaml

Keep (do NOT revert)

• fix: emit explicit dark-scope rules instead of light-dark() in tokens #4864 / e519ff2 — emitting explicit dark-scope rules instead of light-dark(). Better hygiene regardless of bundler and worth keeping.

Follow-up

Pin vite in .github/dependabot.yml to ignore version-update:semver-major so the next major doesn't auto-merge before we've validated the upgrade.

The re-attempt of the Vite 8 upgrade is tracked separately.

[pomfrida]

Closing — the Figma token sync regression has a one-line fix in #4883 (externalize dotenv and Node built-ins in eds-tokens-sync/vite.config.ts), and the light-dark() regression was already addressed in #4864. With both known issues resolved, the case for reverting Vite 8 is gone.