feat(apps): MagicMirror as a Void app (#/mirror, mirror.hynesy.com)

Embed MagicMirror² (CT 111) via the shared embedView factory, exposed at
mirror.hynesy.com through Traefik + CF Access. Traefik mirror-frame middleware
swaps MM's X-Frame-Options for a CSP frame-ancestors allowing the Void origins.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

public/components/sidebar.js

@@ -133,7 +133,8 @@ export function renderSidebar(root) {
       navItem('Timelapse', '/timelapse'),
       navItem('AI Usage', '/ai-usage'),
       navItem('OBD2', '/obd2'),
-      navItem('Links', '/links')
+      navItem('Links', '/links'),
+      navItem('MagicMirror', '/mirror')
     )
   );