Add Docker Compose setup

serve.js

@@ -0,0 +1,24 @@
+// Minimal static server for local preview. Run: node serve.js [port]
+const http = require("http");
+const fs = require("fs");
+const path = require("path");
+
+const ROOT = __dirname;
+const PORT = process.env.PORT || process.argv[2] || 8011;
+const TYPES = {
+  ".html": "text/html", ".js": "text/javascript", ".css": "text/css",
+  ".db": "application/octet-stream", ".wasm": "application/wasm",
+  ".json": "application/json",
+};
+
+http.createServer((req, res) => {
+  let p = decodeURIComponent(req.url.split("?")[0]);
+  if (p === "/") p = "/index.html";
+  const file = path.join(ROOT, p);
+  if (!file.startsWith(ROOT)) { res.writeHead(403); return res.end(); }
+  fs.readFile(file, (err, data) => {
+    if (err) { res.writeHead(404); return res.end("Not found"); }
+    res.writeHead(200, { "Content-Type": TYPES[path.extname(file)] || "application/octet-stream" });
+    res.end(data);
+  });
+}).listen(PORT, () => console.log(`http://localhost:${PORT}`));