Initial commit: code playground with multi-framework support

Express + SQLite backend with Monaco editor frontend.
Supports HTML/CSS/JS, TypeScript, React (JSX/TSX), Vue SFC,
and Svelte with live preview, console output, save/fork/share.

Includes CSS preprocessors (SCSS, Less), framework-specific
compilation (Babel, TypeScript, Svelte compiler), and
CDN-loaded runtime libraries for preview rendering.

public/js/api.js

@@ -0,0 +1,29 @@
+const BASE = '/api/fiddles';
+
+async function request(url, opts = {}) {
+  const res = await fetch(url, {
+    headers: { 'Content-Type': 'application/json' },
+    ...opts,
+  });
+  if (!res.ok) {
+    const err = await res.json().catch(() => ({ error: res.statusText }));
+    throw new Error(err.error || res.statusText);
+  }
+  return res.json();
+}
+
+export function createFiddle(data) {
+  return request(BASE, { method: 'POST', body: JSON.stringify(data) });
+}
+
+export function loadFiddle(id) {
+  return request(`${BASE}/${id}`);
+}
+
+export function updateFiddle(id, data) {
+  return request(`${BASE}/${id}`, { method: 'PUT', body: JSON.stringify(data) });
+}
+
+export function listFiddles() {
+  return request(BASE);
+}