per-source polling, initial client state, webhook, preview, client tracking

- per-source poll intervals: spawn task per source with own interval,
  manager re-checks sources every 30s for add/remove
- initial screen update on TCP connect: send layout + widget states
- client tracking: ClientRegistry port, GET /api/clients, dashboard list
- webhook adapter: POST /api/webhook/{source_id} feeds data into projection
- widget preview: GET /api/widgets/{id}/preview returns current state
- serve SPA from Axum: ServeDir + index.html fallback via KFRAME_SPA_DIR
- layout builder delete confirmation with AlertDialog
- form validation: required fields disable save button
- guide page at /guide
- fix architecture: ClientDto to api-types, ClientRegistry + WidgetStateReader
  ports in domain, DataProjection has internal Mutex, no adapter cross-deps
- ESP32: full screen clear on layout change (stale pixel fix)

crates/adapters/http-api/tests/api_tests.rs

@@ -1,15 +1,21 @@
+use application::DataProjection;
 use axum::body::Body;
 use axum::http::{Request, StatusCode};
 use config_memory::MemoryConfigStore;
 use http_api::{AppState, router};
 use std::sync::Arc;
-use tcp_server::TcpEventBus;
+use tcp_server::{ClientTracker, TcpBroadcaster, TcpEventBus};
 use tower::ServiceExt;
 
 fn test_app() -> axum::Router {
-    let config = Arc::new(MemoryConfigStore::new());
-    let events = Arc::new(TcpEventBus::new(16));
-    let state = AppState { config, events };
+    let state = AppState {
+        config: Arc::new(MemoryConfigStore::new()),
+        events: Arc::new(TcpEventBus::new(16)),
+        widget_states: Arc::new(DataProjection::new()),
+        broadcaster: Arc::new(TcpBroadcaster::new(16)),
+        clients: Arc::new(ClientTracker::new()),
+        spa_dir: None,
+    };
     router(state)
 }