Initial commit: Arduino Uno Q USB Audio Synth project

- USB gadget (UAC1 + MIDI) with boot persistence
- USB host mode with auto-detection
- Pure Data synth patch with ALSA + UDP netreceive MIDI input
- MIDI rawmidi-to-UDP bridge (midi-bridge.py)
- LED matrix visualization (led-matrix-viz.py via arduino-router RPC)
- MCU sketch for LED matrix control (Arduino_RouterBridge + ArduinoGraphics)
- Conftest/OPA Rego policy validation suite for .pd files
- gen_synth_pd.py: programmatic .pd file generator
- System services: midi-bridge, led-matrix-viz, pd-synth-auto, usb-role-detect
- Justfile with deploy, enable, diagnostic recipes
- Diagnostic script (diag.sh)

system/reset-usb-gadget.sh

@@ -0,0 +1,38 @@
+#!/bin/bash
+set -euo pipefail
+
+# Reset USB controller and re-bind gadget
+UDC="4e00000.usb"
+GADGET="/sys/kernel/config/usb_gadget/g1"
+
+# Find the driver binding
+DRIVER=""
+for d in /sys/bus/platform/drivers/*/; do
+    dname=$(basename "$d")
+    if [ -L "$d/$UDC" ] 2>/dev/null; then
+        DRIVER="$dname"
+        break
+    fi
+done
+
+if [ -z "$DRIVER" ]; then
+    # Try looking at the UDC device itself
+    UDC_PATH=$(readlink -f /sys/class/udc/$UDC/device 2>/dev/null || echo "")
+    if [ -n "$UDC_PATH" ]; then
+        DRIVER=$(basename "$(dirname "$UDC_PATH")" 2>/dev/null || echo "")
+    fi
+fi
+
+echo "Driver: ${DRIVER:-unknown}"
+
+# Unbind
+if [ -n "$DRIVER" ]; then
+    echo "$UDC" > "/sys/bus/platform/drivers/$DRIVER/unbind" 2>/dev/null && echo "Unbound" || echo "Unbind failed"
+    sleep 2
+    echo "$UDC" > "/sys/bus/platform/drivers/$DRIVER/bind" 2>/dev/null && echo "Rebound" || echo "Rebind failed"
+    sleep 1
+fi
+
+# Bind gadget
+echo "$UDC" > "$GADGET/UDC" 2>&1 && echo "Gadget bound" || echo "Gadget bind failed"
+cat /sys/class/udc/$UDC/state