Add local test server

scripts/serve.mjs

@@ -0,0 +1,16 @@
+// Local test server for dist/ with the cross-origin isolation headers.
+import { createServer } from 'node:http';
+import { readFile } from 'node:fs/promises';
+import { join, extname } from 'node:path';
+const dist = new URL('../dist/', import.meta.url).pathname;
+const types = { '.html': 'text/html', '.js': 'text/javascript', '.css': 'text/css', '.wasm': 'application/wasm', '.png': 'image/png', '.webmanifest': 'application/manifest+json' };
+createServer(async (req, res) => {
+  let p = decodeURIComponent(new URL(req.url, 'http://x').pathname);
+  if (p.endsWith('/')) p += 'index.html';
+  try {
+    const body = await readFile(join(dist, p));
+    res.writeHead(200, { 'Content-Type': types[extname(p)] || 'application/octet-stream',
+      'Cross-Origin-Opener-Policy': 'same-origin', 'Cross-Origin-Embedder-Policy': 'require-corp' });
+    res.end(body);
+  } catch { res.writeHead(404); res.end(); }
+}).listen(process.env.PORT || 4173, () => console.log('serving dist on', process.env.PORT || 4173));