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/media/src/error.rs

@@ -4,6 +4,8 @@ pub enum MediaError {
     Request(#[from] reqwest::Error),
     #[error("no url configured")]
     NoUrl,
+    #[error("missing field in headers: {0}")]
+    MissingField(&'static str),
     #[error("parse: {0}")]
     Parse(String),
 }

crates/adapters/media/src/lib.rs

@@ -2,33 +2,61 @@ mod error;
 
 pub use error::MediaError;
 
-use std::collections::BTreeMap;
 use domain::{DataSource, DataSourcePort, Value};
+use std::collections::BTreeMap;
 
 pub struct MediaAdapter {
     client: reqwest::Client,
 }
 
-impl MediaAdapter {
-    pub fn new() -> Self {
+impl Default for MediaAdapter {
+    fn default() -> Self {
         Self {
             client: reqwest::Client::new(),
         }
     }
 }
 
+impl MediaAdapter {
+    pub fn new() -> Self {
+        Self::default()
+    }
+}
+
+fn find_header<'a>(headers: &'a [(String, String)], key: &str) -> Option<&'a str> {
+    headers
+        .iter()
+        .find(|(k, _)| k.eq_ignore_ascii_case(key))
+        .map(|(_, v)| v.as_str())
+}
+
+fn subsonic_token(password: &str, salt: &str) -> String {
+    format!("{:x}", md5::compute(format!("{password}{salt}")))
+}
+
 impl DataSourcePort for MediaAdapter {
     type Error = MediaError;
 
     async fn poll(&self, source: &DataSource) -> Result<Value, Self::Error> {
         let base_url = source.config.url.as_ref().ok_or(MediaError::NoUrl)?;
-        let api_key = source.config.api_key.as_deref().unwrap_or("");
+        let username = find_header(&source.config.headers, "username")
+            .ok_or(MediaError::MissingField("username"))?;
+        let password = find_header(&source.config.headers, "password")
+            .ok_or(MediaError::MissingField("password"))?;
+
+        let salt: String = (0..12).map(|_| fastrand::alphanumeric()).collect();
+        let token = subsonic_token(password, &salt);
 
         let url = format!(
-            "{base_url}/rest/getNowPlaying.view?u=kframe&t={api_key}&s=salt&v=1.16.1&c=kframe&f=json"
+            "{base_url}/rest/getNowPlaying.view?u={username}&t={token}&s={salt}&v=1.16.1&c=kframe&f=json"
         );
 
-        let resp = self.client.get(&url).send().await.map_err(MediaError::Request)?;
+        let resp = self
+            .client
+            .get(&url)
+            .send()
+            .await
+            .map_err(MediaError::Request)?;
         let json: serde_json::Value = resp.json().await.map_err(MediaError::Request)?;
 
         let entries = json["subsonic-response"]["nowPlaying"]["entry"]
@@ -45,15 +73,18 @@ impl DataSourcePort for MediaAdapter {
         let entry = &entries[0];
         let mut result = BTreeMap::new();
         result.insert("playing".into(), Value::Bool(true));
-        result.insert("title".into(), Value::String(
-            entry["title"].as_str().unwrap_or("Unknown").into()
-        ));
-        result.insert("artist".into(), Value::String(
-            entry["artist"].as_str().unwrap_or("Unknown").into()
-        ));
-        result.insert("album".into(), Value::String(
-            entry["album"].as_str().unwrap_or("Unknown").into()
-        ));
+        result.insert(
+            "title".into(),
+            Value::String(entry["title"].as_str().unwrap_or("Unknown").into()),
+        );
+        result.insert(
+            "artist".into(),
+            Value::String(entry["artist"].as_str().unwrap_or("Unknown").into()),
+        );
+        result.insert(
+            "album".into(),
+            Value::String(entry["album"].as_str().unwrap_or("Unknown").into()),
+        );
 
         if let Some(duration) = entry["duration"].as_u64() {
             result.insert("duration".into(), Value::Number(duration as f64));