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/_inner-build-niri-live.sh

@@ -31,6 +31,16 @@ command -v xbps-install.static >/dev/null \
 
 mkdir -p "$(dirname "$OUT_ISO")"
 
+# ── Audio and Theme Support ──────────────────────────────────────────────
+# The Niri live ISO includes:
+# 1. sof-firmware: Intel Sound Open Firmware (required for modern Intel audio)
+# 2. alsa-ucm-conf: ALSA Use Case Manager profiles (sof-soundwire for SoundWire hardware)
+# 3. Removed forced audio kernel parameters: The kernel auto-selects SOF/HDA/AVS
+#    based on hardware IDs. Forced parameters (snd-intel-dspcfg.dsp_driver=1)
+#    broke audio on SoundWire platforms like XPS 9700.
+#    See iso/build-niri-live-iso.sh (BOOT_CMDLINE) and docs/KERNEL7_AUDIO_XPS9700.md
+# 4. Dark theme dconf database: Compiled here during ISO build.
+
 # Compile dconf system-db using Void's own dconf binary inside the target
 # rootfs. The Niri live builder writes /etc/dconf/db/local.d/01-dark-theme,
 # but the live system will not report the dark theme unless the GVDB is