feat(audio): add list_audio_devices command; wire device into start_recording

list_audio_devices runs the (blocking, COM-based) enumeration off the
async runtime via spawn_blocking, same pattern as import_pst_core.
start_recording now passes settings.audio_output_device through to
WasapiCapture::start instead of always capturing the default device.

src-tauri/src/commands.rs

@@ -62,6 +62,7 @@ fn default_settings() -> Settings {
         retention_max_size_gb: None,
         pst_last_path: None,
         pst_auto_sync: false,
+        audio_output_device: None,
     }
 }
 
@@ -286,7 +287,12 @@ pub async fn start_recording(
     // Level updates + device-change notices (FR-CAP-5/6); low-volume, forwarded to events below.
     let (event_tx, event_rx) = std::sync::mpsc::sync_channel::<crate::audio::CaptureEvent>(8);
     let capture = WasapiCapture
-        .start(&wav_path, frame_tx, event_tx)
+        .start(
+            &wav_path,
+            settings.audio_output_device.as_deref(),
+            frame_tx,
+            event_tx,
+        )
         .map_err(|e| WaError::new("audio", e.to_string()))?;
 
     // Fire-and-forget: exits on its own once `event_tx` drops at capture stop;
@@ -905,6 +911,18 @@ pub async fn hardware_status() -> WaResult<serde_json::Value> {
     }))
 }
 
+/// Lists active render (playback) devices for the "Audio Devices" picker
+/// (Settings ▸ Hardware) — loopback-only, matching the app's only capture
+/// path (FR-CAP-1). Runs off the async runtime thread since device
+/// enumeration is a blocking COM call.
+#[tauri::command]
+pub async fn list_audio_devices() -> WaResult<Vec<crate::audio::AudioDeviceInfo>> {
+    tauri::async_runtime::spawn_blocking(crate::audio::list_render_devices)
+        .await
+        .map_err(|e| WaError::new("audio", e.to_string()))?
+        .map_err(|e| WaError::new("audio", e.to_string()))
+}
+
 #[derive(Deserialize)]
 pub struct SetPreferredBackendArgs {
     pub backend: String, // "auto"|"npu"|"nvidia"|"amd"|"intel"|"cpu"