Splitting the library code

[bmthd]

https://zenn.dev/toaru_fe/articles/5128fb6a6c21d2

[bmthd]

  build: {
    lib: {
      entry: {
        index: resolve(__dirname, "src/index.ts"),
      },
      formats: ["es", "cjs"],
    },
    rollupOptions: {
      output: {
        preserveModules: true,
        preserveModulesRoot: "src",
      },
      external: [
        ...Object.keys(dependencies),
        ...Object.keys(peerDependencies),
      ],
    },
  },
  plugins: [react()],
});