[FEAT] First functional version.

api/router.php

@@ -0,0 +1,12 @@
+<?php
+
+// Router script for PHP built-in server
+$uri = parse_url($_SERVER['REQUEST_URI'], PHP_URL_PATH);
+
+// Serve existing files directly
+if ($uri !== '/' && file_exists(__DIR__ . $uri)) {
+    return false;
+}
+
+// Route everything through index.php
+require __DIR__ . '/index.php';