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/adapters/tcp-server/src/broadcaster.rs

@@ -1,12 +1,7 @@
-use tokio::sync::broadcast;
-use domain::{
-    BroadcastPort, Layout, WidgetId, WidgetState,
-};
-use protocol::{
-    ServerMessage, WidgetDescriptor, WireDisplayHint, WireLayoutNode,
-    encode,
-};
 use crate::error::TcpServerError;
+use domain::{BroadcastPort, Layout, WidgetId, WidgetState};
+use protocol::{ServerMessage, WidgetDescriptor, WireDisplayHint, WireLayoutNode, encode};
+use tokio::sync::broadcast;
 
 pub struct TcpBroadcaster {
     tx: broadcast::Sender<Vec<u8>>,
@@ -37,13 +32,14 @@ impl BroadcastPort for TcpBroadcaster {
         widgets: &[(WidgetId, WidgetState)],
     ) -> Result<(), Self::Error> {
         let wire_layout: WireLayoutNode = (&layout.root).into();
-        let wire_widgets: Vec<WidgetDescriptor> = widgets.iter().map(|(id, state)| {
-            WidgetDescriptor {
+        let wire_widgets: Vec<WidgetDescriptor> = widgets
+            .iter()
+            .map(|(id, state)| WidgetDescriptor {
                 id: *id,
                 display_hint: WireDisplayHint::IconValue,
                 state: state.into(),
-            }
-        }).collect();
+            })
+            .collect();
 
         let msg = ServerMessage::ScreenUpdate {
             layout: wire_layout,
@@ -58,13 +54,14 @@ impl BroadcastPort for TcpBroadcaster {
         &self,
         updates: &[(WidgetId, WidgetState)],
     ) -> Result<(), Self::Error> {
-        let wire_widgets: Vec<WidgetDescriptor> = updates.iter().map(|(id, state)| {
-            WidgetDescriptor {
+        let wire_widgets: Vec<WidgetDescriptor> = updates
+            .iter()
+            .map(|(id, state)| WidgetDescriptor {
                 id: *id,
                 display_hint: WireDisplayHint::IconValue,
                 state: state.into(),
-            }
-        }).collect();
+            })
+            .collect();
 
         let msg = ServerMessage::DataUpdate {
             widgets: wire_widgets,