fix(frontend): hide CircuitJS toolbar & menu bar in lesson embeds

Append &hideMenu=true to the circuitjs.html iframe src used by
renderCircuitEmbeds so lesson content embeds render clean without
the toolbar and menu bar. The embed path in CircuitEditor.svelte
is untouched, so the editor keeps its full toolbar.

Verified:
- Bundle contains embed URL (with hideMenu=true) and editor URL
  (without) as separate variants
- svelte-check: 0 errors
- /lesson/rangkaian_dasar returns 200 on the running stack

frontend/src/lib/actions/renderCircuitEmbeds.ts

@@ -18,7 +18,7 @@ function loadCircuitEmbed(div: HTMLElement) {
 	const isDark = document.documentElement.getAttribute('data-theme') === 'dark';
 
 	const iframe = document.createElement('iframe');
-	iframe.src = `/circuitjs1/circuitjs.html?whiteBackground=${!isDark}`;
+	iframe.src = `/circuitjs1/circuitjs.html?whiteBackground=${!isDark}&hideMenu=true`;
 	iframe.style.width = '100%';
 	iframe.style.height = '100%';
 	iframe.style.border = 'none';