Ships DnD + the JS hooks (`assets/js/athanor.js`) and `package.json`
so consumers can `import "athanor"` through esbuild module resolution.

The 0.1.0-beta.1 tarball pre-dated the DnD work and did not include
`assets/` or `package.json`, so downstream prod builds (Amplify Docker)
could not resolve the bare module import.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>