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.
- Permanent rename: led-matrix-bridge.ino → sketch.ino (Arduino CLI convention)
- Add just flash-sketch recipe for compiling/flashing MCU via board's arduino-cli
- Run via post-merge hooks for auto-deploy