feat!: Packaging changes.

Specifically:

* Remove UMD module support. Per caniuse.com, all browsers that
support WebAssembly also support ES6, save Firefox < 54, which is now
over 5 years old.

* Add `files` to the package config and ensure that all files in
`dist` and `wasm_dist` are included in the package.

Note that Storybook expects CommonJS format, and adding `type: module`
to `package.json` causes it to break. This will be fixed in Storybook
v7, but until then, we implement the workaround described here:

storybookjs/storybook#11587 (comment)

package.json

@@ -3,14 +3,15 @@
   "sideEffects": false,
   "version": "0.0.2",
   "description": "",
-  "main": "./dist/tidy.umd.js",
-  "module": "./dist/tidy.es.mjs",
+  "type": "module",
+  "files": ["dist/**/*", "wasm_dist/**/*"],
+  "main": "./dist/tidy.js",
+  "module": "./dist/tidy.js",
   "types": "./dist/index.d.ts",
   "source": "./src/index.ts",
   "exports": {
     ".": {
-      "import": "./dist/tidy.es.mjs",
-      "require": "./dist/tidy.umd.js"
+      "import": "./dist/tidy.js"
     }
   },
   "scripts": {
@@ -25,13 +26,7 @@
     "build-storybook": "build-storybook",
     "bench:wasm": "node --expose-gc test/benchmark.mjs"
   },
-  "keywords": [
-    "tree",
-    "visualization",
-    "wasm",
-    "mindmap",
-    "rust"
-  ],
+  "keywords": ["tree", "visualization", "wasm", "mindmap", "rust"],
   "license": "MIT",
   "author": "Zixuan Chen",
   "repository": {

vite.config.ts

@@ -30,13 +30,8 @@ export default defineConfig({
     lib: {
       entry: path.resolve(__dirname, 'src/index.ts'),
       name: 'tidy',
-      fileName: (format) => {
-        if (format === 'es') {
-          return 'tidy.es.mjs';
-        }
-
-        return `tidy.${format}.js`;
-      },
+      fileName: 'tidy',
+      formats: ['es'],
     },
     rollupOptions: {
       external: ['react'],