fixes for vite / vitest builds

[seanrcollings]

vitest has to use node's dependency resolution strategies, which don't always work the same way you'd expect that vite normally worked when bundling dependencies. This PR:

• Swaps @atomicjolt/hooks to build to es modules instead of common js
• Adds some additional metadata in the package.json to help node
• Includes the source TS assets in the final bundle for elements & hooks so that sourcemaps produced during the build actually point to something. This is not strictly necessary, but it stops vitest from emitting a bunch of warnings about missing source files & it should improve developer experience as the source files are actually present.