Fix onboard audio: apply ALSA UCM HiFi verb before Pd start

- Add alsaucm -c hw:0 set _verb HiFi to start-synth.sh (onboard mode)
- Add UCM verb to install.sh
- Add UCM verb to justfile fix-ucm recipe
- Without this, the DSP audio routing is not configured and no sound
  reaches the headphone output

install.sh

@@ -9,10 +9,29 @@ for svc in "${SERVICES[@]}"; do
     sudo cp "$REPO/system/$svc.service" /etc/systemd/system/
 done
 
+# Apply UCM HiFi verb to configure DSP audio routing
+if command -v alsaucm &>/dev/null; then
+    alsaucm -c hw:0 set _verb HiFi && echo "[OK] UCM HiFi verb applied"
+fi
+
 # Fix UCM bug (must survive OS updates)
 FILE=/usr/share/alsa/ucm2/codecs/qcom-lpass/rx-macro/HeadphoneEnableSeq.conf
+NEED_FIX=0
+# Remove invalid RX HPH Mode line
 if grep -q "RX HPH Mode" "$FILE" 2>/dev/null; then
     sudo sed -i '/RX HPH Mode/d' "$FILE"
+    NEED_FIX=1
+fi
+# Add missing RX INT0_1/INT1_1 INTERP controls (blocks audio on some boards)
+if ! grep -q "RX INT0_1 INTERP" "$FILE" 2>/dev/null; then
+    echo '    cset "name=RX INT0_1 INTERP" "RX INT0_1 MIX1"' | sudo tee -a "$FILE" >/dev/null
+    NEED_FIX=1
+fi
+if ! grep -q "RX INT1_1 INTERP" "$FILE" 2>/dev/null; then
+    echo '    cset "name=RX INT1_1 INTERP" "RX INT1_1 MIX1"' | sudo tee -a "$FILE" >/dev/null
+    NEED_FIX=1
+fi
+if [ "$NEED_FIX" = "1" ]; then
     echo "[OK] UCM HeadphoneEnableSeq patched"
 fi