fix: add Bridge.run() to loop() so MCU processes incoming RPCs

Without Bridge.run() in loop(), the MCU never reads incoming
draw_frame requests from the router. First frame goes through
during setup handshake, but subsequent frames fill the router's
send buffer and the viz stalls.

sketch/sketch.ino

@@ -121,5 +121,6 @@ void setup() {
 }
 
 void loop() {
-  delay(1000);
+  Bridge.run();
+  delay(1);
 }