fix(slint): correct BP marking and widen the output-device list

The BP badge marked every ALSA device; it now marks only the direct
hardware PCMs (hw:/front:/iec958:/hdmi:), matching Tauri — sysdefault
and plug devices are not bit-perfect. The device list also opens at
480px (right-anchored) so the full card + PCM id name is readable
instead of being elided in a 300px control.

cc

crates/qbz-slint/src/settings.rs

@@ -156,12 +156,20 @@ struct DeviceList {
     bp: Vec<bool>,
 }
 
-/// Whether a device can deliver bit-perfect playback on `backend`. ALSA
-/// enumerates real `hw:` cards (always capable); PipeWire reports a
-/// hardware flag per node; PulseAudio always mixes, so never capable.
+/// Whether a device can deliver bit-perfect playback on `backend`. On
+/// ALSA only the direct-hardware PCMs qualify (`hw:` / `front:` and the
+/// digital `iec958:` / `hdmi:`) — `sysdefault:`, `plughw:` and friends
+/// route through converting plugins. PipeWire reports a hardware flag
+/// per node; PulseAudio always mixes, so never capable.
 fn device_is_bit_perfect(backend: AudioBackendType, device: &qbz_audio::AudioDevice) -> bool {
     match backend {
-        AudioBackendType::Alsa => true,
+        AudioBackendType::Alsa => {
+            let id = device.id.to_ascii_lowercase();
+            id.starts_with("hw:")
+                || id.starts_with("front:")
+                || id.starts_with("iec958:")
+                || id.starts_with("hdmi:")
+        }
         AudioBackendType::PipeWire => device.is_hardware,
         AudioBackendType::Pulse | AudioBackendType::SystemDefault => false,
     }

crates/qbz-slint/ui/primitives/QbzSelect.slint

@@ -27,9 +27,16 @@ export component QbzSelect inherits Rectangle {
     in property <[bool]> badges: [];
     in property <int> current-index: 0;
     in property <length> menu-width: 240px;
+    // Optional: a wider open list than the collapsed control, for long
+    // option labels (device names). 0px keeps the list at `menu-width`.
+    in property <length> popup-width: 0px;
     in property <bool> enabled: true;
     callback selected(int);
 
+    // Resolved width of the open list.
+    private property <length> list-width:
+        root.popup-width > root.menu-width ? root.popup-width : root.menu-width;
+
     width: root.menu-width;
     height: 34px;
     border-radius: Radius.sm;
@@ -79,9 +86,11 @@ export component QbzSelect inherits Rectangle {
     }
 
     popup := PopupWindow {
-        x: 0;
+        // Right-anchored so a list wider than the control grows leftward
+        // and stays on-screen.
+        x: root.menu-width - root.list-width;
         y: root.height + 4px;
-        width: root.menu-width;
+        width: root.list-width;
         height: root.options.length * 32px + 10px;
 
         Rectangle {

crates/qbz-slint/ui/settings/AudioSettings.slint

@@ -95,6 +95,9 @@ export component AudioSettings inherits VerticalLayout {
         description: @tr("The DAC or sound device that receives audio.");
         QbzSelect {
             menu-width: 300px;
+            // Device labels run long; open the list wider so the full
+            // name (card + ALSA PCM id) is readable.
+            popup-width: 480px;
             options: SettingsState.devices;
             badges: SettingsState.device-bp;
             current-index: SettingsState.device-index;