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

justfile

@@ -149,8 +149,24 @@ reboot:
 # Must run once after OS updates or first install.
 fix-ucm:
     @ssh {{SSH_OPTS}} "{{BOARD_USER}}@{{BOARD_HOST}}" "\
-        if grep -q 'RX HPH Mode' /usr/share/alsa/ucm2/codecs/qcom-lpass/rx-macro/HeadphoneEnableSeq.conf 2>/dev/null; then \
-            echo '{{BOARD_PASS}}' | sudo -S sed -i '/RX HPH Mode/d' /usr/share/alsa/ucm2/codecs/qcom-lpass/rx-macro/HeadphoneEnableSeq.conf && \
+        echo '{{BOARD_PASS}}' | sudo -S alsaucm -c hw:0 set _verb HiFi 2>/dev/null && \
+        echo '[OK] UCM verb applied' || \
+        echo '[WARN] UCM verb failed' && \
+        FILE=/usr/share/alsa/ucm2/codecs/qcom-lpass/rx-macro/HeadphoneEnableSeq.conf && \
+        FIXED=0 && \
+        if grep -q 'RX HPH Mode' \"\$FILE\" 2>/dev/null; then \
+            echo '{{BOARD_PASS}}' | sudo -S sed -i '/RX HPH Mode/d' \"\$FILE\" && \
+            FIXED=1; \
+        fi && \
+        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 && \
+            FIXED=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 && \
+            FIXED=1; \
+        fi && \
+        if [ \"\$FIXED\" = \"1\" ]; then \
             sudo systemctl restart wireplumber && \
             echo '[OK] UCM HeadphoneEnableSeq patched'; \
         else \