feat(simulator): add GUI runner, stubs, and workspace assets

Add host simulator scaffolding, examples, and docs so led-driver main can run end-to-end with MicroPython module stubs.

Co-authored-by: Cursor <cursoragent@cursor.com>

led_driver_sim_hook.py

@@ -0,0 +1,17 @@
+"""Host-only: led-simulator registers the Microdot app so Stop can call shutdown()."""
+
+_app = None
+
+
+def register_app(app):
+    global _app
+    _app = app
+
+
+def get_app():
+    return _app
+
+
+def clear_app():
+    global _app
+    _app = None