Add a developer-focused demo vault that shows how Advanced Debug Mode enriches
the DevTools console. Notes are numbered basic to advanced and cover debug mode,
long stack traces (with a Run button that throws through async boundaries), async
long stack traces, long-running-task timeouts, mobile DevTools, debug namespaces,
and every setting. A no-app integration suite keeps the notes in sync with the
PluginSettings surface. The root README documents the three ways to open it.
