fix: order "types" first in package.json exports (#330)

Export conditions are matched top-to-bottom, first match wins. With
`"import"` and `"require"` listed before `"types"`, the types condition
was unreachable — consumers resolving through `"exports"`
(`moduleResolution: node16` / `bundler`) never picked up the
declarations, and esbuild warned on every `vitest` run:

```
▲ [WARNING] The condition "types" here will never be used as it comes after both "import" and "require" [package.json]
```

Reordering `"types"` to the top fixes it. The top-level `"types"` field
is kept as the fallback for legacy `moduleResolution: node`.

## Verification

- `yarn vitest run` no longer emits the warning (0 occurrences).
- No behavior change to the emitted bundles — this only affects
resolution order.