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/config_service_tests.rs

@@ -1,13 +1,12 @@
 mod support;
 
-use std::time::Duration;
-use domain::{
-    ConfigRepository, DisplayHint, DomainEvent, KeyMapping, WidgetConfig,
-    DataSource, DataSourceConfig, DataSourceType,
-    Layout, LayoutNode, ContainerNode, LayoutChild, Direction, Sizing,
-    LayoutPreset,
-};
 use application::ConfigService;
+use domain::{
+    ConfigRepository, ContainerNode, DataSource, DataSourceConfig, DataSourceType, Direction,
+    DisplayHint, DomainEvent, KeyMapping, Layout, LayoutChild, LayoutNode, LayoutPreset, Sizing,
+    WidgetConfig,
+};
+use std::time::Duration;
 use support::{InMemoryConfigRepository, InMemoryEventPublisher};
 
 #[tokio::test]
@@ -21,9 +20,10 @@ async fn create_widget_persists_and_emits_event() {
         "weather".into(),
         DisplayHint::IconValue,
         1,
-        vec![
-            KeyMapping { source_path: "$.temp".into(), target_key: "temperature".into() },
-        ],
+        vec![KeyMapping {
+            source_path: "$.temp".into(),
+            target_key: "temperature".into(),
+        }],
     );
 
     service.create_widget(config).await.unwrap();
@@ -99,8 +99,14 @@ async fn update_layout_persists_and_emits_event() {
             gap: 4,
             padding: 2,
             children: vec![
-                LayoutChild { sizing: Sizing::Flex(1), node: LayoutNode::Leaf(1) },
-                LayoutChild { sizing: Sizing::Flex(1), node: LayoutNode::Leaf(2) },
+                LayoutChild {
+                    sizing: Sizing::Flex(1),
+                    node: LayoutNode::Leaf(1),
+                },
+                LayoutChild {
+                    sizing: Sizing::Flex(1),
+                    node: LayoutNode::Leaf(2),
+                },
             ],
         }),
     };
@@ -111,7 +117,10 @@ async fn update_layout_persists_and_emits_event() {
     assert_eq!(stored, Some(layout));
 
     assert_eq!(events.emitted().len(), 1);
-    assert!(matches!(events.emitted()[0], DomainEvent::LayoutChanged { .. }));
+    assert!(matches!(
+        events.emitted()[0],
+        DomainEvent::LayoutChanged { .. }
+    ));
 }
 
 #[tokio::test]
@@ -125,9 +134,10 @@ async fn load_preset_replaces_active_layout() {
             direction: Direction::Column,
             gap: 0,
             padding: 0,
-            children: vec![
-                LayoutChild { sizing: Sizing::Flex(1), node: LayoutNode::Leaf(5) },
-            ],
+            children: vec![LayoutChild {
+                sizing: Sizing::Flex(1),
+                node: LayoutNode::Leaf(5),
+            }],
         }),
     };
 
@@ -146,6 +156,9 @@ async fn load_preset_replaces_active_layout() {
 
     let emitted = events.emitted();
     assert_eq!(emitted.len(), 2);
-    assert!(matches!(emitted[0], DomainEvent::LayoutPresetLoaded { id: 1 }));
+    assert!(matches!(
+        emitted[0],
+        DomainEvent::LayoutPresetLoaded { id: 1 }
+    ));
     assert!(matches!(emitted[1], DomainEvent::LayoutChanged { .. }));
 }