chore(site): add static export preview script

docs/package.json

@@ -4,6 +4,7 @@
   "license": "Apache-2.0",
   "scripts": {
     "dev": "next dev",
+    "preview": "node scripts/preview-server.mjs",
     "content:check": "node scripts/verify-doc-content.mjs",
     "prebuild": "node scripts/verify-doc-content.mjs",
     "build": "next build",

docs/scripts/preview-server.mjs

@@ -0,0 +1,66 @@
+// Local preview for the static export, mimicking Cloudflare Workers asset
+// resolution: exact file first, then /foo -> /foo.html, then /foo/ ->
+// /foo/index.html, and unknown paths fall back to 404.html like
+// not_found_handling: "404-page". Run `pnpm build` before this script.
+//
+// Usage: node scripts/preview-server.mjs [port]
+import { createServer } from "node:http";
+import { readFile, stat } from "node:fs/promises";
+import { extname, join, resolve } from "node:path";
+
+const ROOT = resolve(import.meta.dirname, "../out");
+const PORT = Number(process.argv[2] ?? 3000);
+const types = {
+  ".html": "text/html; charset=utf-8",
+  ".js": "text/javascript",
+  ".css": "text/css",
+  ".txt": "text/plain",
+  ".png": "image/png",
+  ".svg": "image/svg+xml",
+  ".webp": "image/webp",
+  ".json": "application/json",
+  ".xml": "application/xml",
+  ".ico": "image/x-icon",
+  ".map": "application/json",
+  ".woff2": "font/woff2",
+};
+
+async function tryFile(rel) {
+  const file = join(ROOT, rel);
+  try {
+    const info = await stat(file);
+    if (!info.isFile()) return null;
+    return { file, type: types[extname(file)] ?? "application/octet-stream" };
+  } catch {
+    return null;
+  }
+}
+
+createServer(async (req, res) => {
+  try {
+    const path = decodeURIComponent(new URL(req.url, "http://localhost").pathname);
+    if (path.includes("..")) {
+      res.writeHead(400);
+      return res.end();
+    }
+    const hit =
+      (await tryFile(path)) ??
+      (path.endsWith("/") ? await tryFile(join(path, "index.html")) : await tryFile(`${path}.html`));
+    if (hit) {
+      res.writeHead(200, { "content-type": hit.type, "cache-control": "no-store" });
+      return res.end(await readFile(hit.file));
+    }
+    const fallback = await tryFile("404.html");
+    if (fallback) {
+      res.writeHead(404, { "content-type": fallback.type, "cache-control": "no-store" });
+      return res.end(await readFile(fallback.file));
+    }
+    res.writeHead(404, { "content-type": "text/plain" });
+    res.end("404");
+  } catch (error) {
+    res.writeHead(500);
+    res.end(String(error));
+  }
+}).listen(PORT, () => {
+  console.log(`Preview serving ${ROOT} at http://localhost:${PORT}`);
+});