CRITICAL FIX: ReinitDevice now uses backend system

PROBLEMA ENCONTRADO:
1. Frontend guardaba backend_type correctamente ✅
2. Player leía settings al inicio (backend_type = None) ✅
3. Usuario cambiaba backend en UI → se guardaba en BD ✅
4. Pero Player en memoria tenía settings VIEJOS ❌
5. reinit_audio_device usaba legacy CPAL sin backend ❌

SÍNTOMAS:
- "Backend system not configured, using legacy CPAL path"
- "Device '...' not found, using default"
- Audio salía por laptop speakers, no por DAC

SOLUCIÓN IMPLEMENTADA:

1. init_device() ahora intenta backend system primero:
   - Lee thread_settings.backend_type
   - Si configurado, llama try_init_stream_with_backend()
   - Fallback a legacy CPAL si falla

2. reinit_audio_device() recarga settings desde BD:
   - Lee AudioSettings desde database
   - Actualiza Player.audio_settings en memoria
   - Luego llama reinit_device()
   - Garantiza que Player siempre tiene config fresca

AHORA FUNCIONARÁ:
- Cambiar backend → se guarda → se recarga → se usa
- Cambiar device → se guarda → se recarga → se usa
- PULSE_SINK se setea correctamente
- Audio debe salir por Cambridge DAC

TESTING REQUERIDO:
Ir a Settings → Audio → Backend: PipeWire → Device: DacMagic Plus
Reproducir música → debería salir por DAC

src-tauri/src/commands/playback.rs

@@ -536,8 +536,20 @@ pub fn get_audio_output_status(
 pub fn reinit_audio_device(
     device: Option<String>,
     state: tauri::State<'_, crate::AppState>,
+    audio_settings_state: tauri::State<'_, crate::config::audio_settings::AudioSettingsState>,
 ) -> Result<(), String> {
     log::info!("Command: reinit_audio_device {:?}", device);
+
+    // Reload settings from database to ensure Player has latest config (including backend_type)
+    if let Ok(store) = audio_settings_state.store.lock() {
+        if let Ok(fresh_settings) = store.get_settings() {
+            if let Ok(mut player_settings) = state.player.audio_settings.lock() {
+                *player_settings = fresh_settings;
+                log::info!("Reloaded audio settings before reinit (backend_type: {:?})", player_settings.backend_type);
+            }
+        }
+    }
+
     state.player.reinit_device(device)
 }
 

src-tauri/src/player/mod.rs

@@ -590,7 +590,28 @@ impl Player {
             };
 
             // Helper to find and initialize audio device
+            // Try backend system first, fall back to legacy CPAL
             let init_device = |name: &Option<String>, state: &SharedState| -> Option<(OutputStream, rodio::OutputStreamHandle)> {
+                // Try backend system if configured
+                if let Ok(settings) = thread_settings.lock() {
+                    if settings.backend_type.is_some() {
+                        // Use a dummy sample rate/channels for reinit (will be set on next play)
+                        match try_init_stream_with_backend(&settings, 48000, 2) {
+                            Some(Ok(stream)) => {
+                                log::info!("Audio output initialized via backend system");
+                                return Some(stream);
+                            }
+                            Some(Err(e)) => {
+                                log::warn!("Backend system init failed: {}, falling back to legacy", e);
+                            }
+                            None => {
+                                // Backend not configured, continue to legacy path
+                            }
+                        }
+                    }
+                }
+
+                // Legacy CPAL path
                 let device = if let Some(ref name) = name {
                     log::info!("Looking for audio device: {}", name);
                     let found = host.output_devices()