feat(audio): add alsa-utils help modal with distro-specific install commands

- Add check_alsa_utils_installed and get_linux_distro Tauri commands
- Detect Linux distribution from /etc/os-release
- Show appropriate package manager command for each distro
- Add (?) help icon next to ALSA Direct device dropdown in Settings
- Modal explains why alsa-utils is needed for bit-perfect detection
- Updated PKGBUILDs to list alsa-utils as optdepend

packaging/aur/PKGBUILD

@@ -8,7 +8,7 @@ url="https://github.com/vicrodh/qbz"
 license=('MIT')
 depends=('webkit2gtk-4.1' 'gtk3' 'alsa-lib' 'libappindicator-gtk3' 'libxkbcommon' 'openssl')
 optdepends=(
-    'alsa-utils: Better ALSA device names and descriptions'
+    'alsa-utils: Required for bit-perfect device detection and better ALSA device names'
     'pipewire-alsa: PipeWire audio support'
     'pipewire-pulse: PulseAudio compatibility'
 )