The `package.json` is missing the `main` or `exports` fields

Issue

The package.json doesn't filter what files should be packaged and sent the NPM. Therefore, all the source code with .less files is being distributed.

Also, the entry point of the package is not specified using main, module, or exports. That way, it's confusing for the bundlers what should be used and usually they start picking the files from the src:
https://github.com/NUKnightLab/TimelineJS3/blob/c5948d41fd333a1d292ec1c497c38e52ef793013/index.js#L1

So it requires to double-transpile the package in the consuming app and they don't benefit from the transpilation done before publishing anyway 😢

Suggested changes

1. Limit the distributed code only to the dist folder. That will significantly reduce the size of the package.
2. Specify an entry point explicitly and it should point to the transpiled files in the dist.

Smth like this[^1]:

{
  "name": "@knight-lab/timelinejs",
  "version": "4.0.0",
  "type": "module",
  "files": [
    "dist"
  ],
  "exports": {
    ".": {
      "import": "./dist/index.js"
    }
  },
  "main": "./dist/index.js",
  ...  

Start by inspecting package.json, the existing dist folder, and the referenced index.js entry point. Check the package contents that would be published and how the current build output is consumed; done means only the intended dist files are distributed and package imports resolve to the transpiled entry point.