chore(deps): bump major dependencies

- vite 8, @vitejs/plugin-react 6
- react 19 + @types/react / @types/react-dom 19
- jsdom 30 + @types/jsdom 30
- @biomejs/biome 2.5, @playwright/test + playwright-core 1.63

Also applies the new biome 2.5 `useOptionalChain` suggestions it flagged.
TypeScript stays on 5.x because the package declares `typescript: ^5` as a
peer dependency for consumers.

All of these are devDependencies, so there is no consumer-facing break.
Verified: `bun audit` clean, build, typecheck, lint and tests pass (only
the pre-existing `main` test failures remain).

Author: lenucksi