chore: automate git worktree setup (shared node_modules, per-worktree dev port)

scripts/find-free-port.mjs

@@ -0,0 +1,23 @@
+import { createServer } from "node:net";
+
+function isFree(port) {
+	return new Promise((resolve) => {
+		const server = createServer();
+		server.once("error", () => resolve(false));
+		server.listen(port, "0.0.0.0", () => {
+			server.close(() => resolve(true));
+		});
+	});
+}
+
+async function findFreePort(start) {
+	let port = start;
+	while (!(await isFree(port))) {
+		port++;
+	}
+	return port;
+}
+
+const start = Number.parseInt(process.argv[2] || process.env.PORT || "3000", 10);
+const port = await findFreePort(start);
+process.stdout.write(String(port));