Add kernel-7 audio diagnostics and verify SOF/UCM completeness

- Add alsa-ucm-conf to installed packages.list (already in live-desktop.list)
- Create KERNEL7_AUDIO_XPS9700.md with comprehensive audio diagnostics guide
- Document kernel parameter choices and SOF/SoundWire fix approach in build scripts
- Includes boot-time dsp_driver=3 test procedure for XPS 9700 kernel 7 compatibility

iso/build-niri-live-iso.sh

@@ -859,6 +859,16 @@ ISO_PKGS=$(grep -vE '^\s*(#|$)' \
     | tr '\n' ' ')
 TS="$(date -u +%Y%m%d)"
 OUT_ISO="${OUTPUT_ISO:-$OUT_DIR/void-live-niri-${TS}.iso}"
+
+# BOOT_CMDLINE notes (kernel audio, GPU, Bluetooth, etc.):
+# • NO forced audio kernel parameters: Removed snd-intel-dspcfg.dsp_driver=1 and snd_hda_intel.dmic_detect=0
+#   because they forced legacy HDA mode, blocking SOF/SoundWire on hardware that needs it (e.g., XPS 9700).
+#   The kernel auto-selects the correct driver (0=auto, 3=SOF, 4=AVS) based on hardware IDs.
+#   Users can override at boot with "snd-intel-dspcfg.dsp_driver=3" if needed.
+#   See docs/KERNEL7_AUDIO_XPS9700.md for diagnostics.
+# • nvidia-drm.modeset=1: Required for nvidia GPU to use atomic mode-setting on Wayland (Niri).
+# • blacklist nouveau: nvidia GPU needs proprietary driver, not nouveau.
+# • btusb.enable_autosuspend=0: Prevent Bluetooth headset dropouts when idle.
 BOOT_CMDLINE="${BOOT_CMDLINE:-live.user=${LIVE_USER} console=tty0 console=ttyS0,115200 nvidia-drm.modeset=1 rd.driver.blacklist=nouveau modprobe.blacklist=nouveau btusb.enable_autosuspend=0}"
 
 echo ">>> running mklive.sh inside docker — output: $OUT_ISO"