add SPA config UI, wire media/rss adapters, event-driven layout push

- React SPA: dashboard, data sources CRUD, widgets CRUD, layout builder,
  presets. TanStack Router + Query, shadcn/ui, Vite proxy to :3000
- wire media + rss adapters into polling loop, remove xtb source type
- media adapter: read username/password from headers, proper subsonic auth
- event handler: subscribe to LayoutChanged, push screen update to clients
- fix clippy warnings across workspace (Default impls, collapsible ifs,
  redundant closures, is_none_or, unused imports)

crates/application/tests/support/mod.rs

@@ -1,10 +1,9 @@
-use std::sync::Mutex;
-use std::collections::HashMap;
 use domain::{
-    ConfigRepository, EventPublisher,
-    DataSource, DataSourceId, Layout, LayoutPreset, LayoutPresetId,
-    WidgetConfig, WidgetId, DomainEvent,
+    ConfigRepository, DataSource, DataSourceId, DomainEvent, EventPublisher, Layout, LayoutPreset,
+    LayoutPresetId, WidgetConfig, WidgetId,
 };
+use std::collections::HashMap;
+use std::sync::Mutex;
 
 pub struct InMemoryConfigRepository {
     widgets: Mutex<HashMap<WidgetId, WidgetConfig>>,
@@ -45,7 +44,10 @@ impl ConfigRepository for InMemoryConfigRepository {
     }
 
     async fn save_widget(&self, config: &WidgetConfig) -> Result<(), Self::Error> {
-        self.widgets.lock().unwrap().insert(config.id, config.clone());
+        self.widgets
+            .lock()
+            .unwrap()
+            .insert(config.id, config.clone());
         Ok(())
     }
 
@@ -59,11 +61,20 @@ impl ConfigRepository for InMemoryConfigRepository {
     }
 
     async fn list_data_sources(&self) -> Result<Vec<DataSource>, Self::Error> {
-        Ok(self.data_sources.lock().unwrap().values().cloned().collect())
+        Ok(self
+            .data_sources
+            .lock()
+            .unwrap()
+            .values()
+            .cloned()
+            .collect())
     }
 
     async fn save_data_source(&self, source: &DataSource) -> Result<(), Self::Error> {
-        self.data_sources.lock().unwrap().insert(source.id, source.clone());
+        self.data_sources
+            .lock()
+            .unwrap()
+            .insert(source.id, source.clone());
         Ok(())
     }
 
@@ -90,7 +101,10 @@ impl ConfigRepository for InMemoryConfigRepository {
     }
 
     async fn save_preset(&self, preset: &LayoutPreset) -> Result<(), Self::Error> {
-        self.presets.lock().unwrap().insert(preset.id, preset.clone());
+        self.presets
+            .lock()
+            .unwrap()
+            .insert(preset.id, preset.clone());
         Ok(())
     }