fix: reduce loop delay to 10ms so __loopHook processes RPCs

Background thread stack (500 bytes) overflows after ~50 draw_frame
calls. __loopHook (called after loop() returns) is the fallback.
With delay(1000), it ran once per second — too slow.
Reducing to delay(10) keeps RPC processing responsive.

sketch/sketch.ino

@@ -121,5 +121,5 @@ void setup() {
 }
 
 void loop() {
-  delay(1000);
+  delay(10);
 }