build: provide `"type": "module"` in `package.json`

[iiio2]

"type": "module" syntax detection is required for performance issue. Node.js doc says, "Syntax detection should have no performance impact on CommonJS modules, but it incurs a slight performance penalty for ES modules; add "type": "module" to the nearest parent package.json file to eliminate the performance cost." That's why I think we may add it in the package.json file.

https://nodejs.org/en/blog/release/v20.19.0#module-syntax-detection-is-now-enabled-by-default