feat(package): add postbuild script to gzip distribution files

package.json

@@ -5,6 +5,7 @@
   "type": "module",
   "scripts": {
     "build": "vite build",
+    "postbuild": "node scripts/gzip-dist.mjs",
     "dev": "vite"
   },
   "dependencies": {

scripts/gzip-dist.mjs

@@ -0,0 +1,32 @@
+import { createReadStream, createWriteStream } from 'node:fs';
+import { readdir, unlink } from 'node:fs/promises';
+import { extname, join } from 'node:path';
+import { pipeline } from 'node:stream/promises';
+import { createGzip } from 'node:zlib';
+
+const EXTS = new Set(['.html', '.js', '.css', '.svg']);
+const DIST = 'dist';
+
+async function* walk(dir) {
+  for (const entry of await readdir(dir, { withFileTypes: true })) {
+    const full = join(dir, entry.name);
+    if (entry.isDirectory()) {
+      yield* walk(full);
+    } else if (EXTS.has(extname(entry.name))) {
+      yield full;
+    }
+  }
+}
+
+let count = 0;
+for await (const file of walk(DIST)) {
+  await pipeline(
+    createReadStream(file),
+    createGzip({ level: 9 }),
+    createWriteStream(`${file}.gz`),
+  );
+  await unlink(file);
+  count++;
+  console.log(`  gzip  ${file}`);
+}
+console.log(`\nGzipped ${count} file${count === 1 ? '' : 's'}.`);