state recovery, polling optimizations, error rendering

widget states cached to SQLite, loaded on startup to seed DataProjection
so server restart preserves last-known data for reconnecting clients.

polling: first poll runs immediately, widget list cached per-task with
30s refresh, static text polled once inline instead of looping.

poll failures propagate WidgetError::SourceUnavailable to clients.
render engine prepends [offline] prefix in accent color, stale data
preserved below.

crates/bootstrap/src/main.rs

@@ -5,12 +5,13 @@ mod polling;
 use anyhow::Result;
 use application::DataProjection;
 use config_sqlite::SqliteConfigStore;
+use domain::ConfigRepository;
 use http_api::AppState;
 use kframe_auth::{Argon2Hasher, AuthConfig, JwtAuthService};
 use secret_store::AesSecretStore;
 use std::sync::Arc;
 use tcp_server::{ClientTracker, TcpBroadcaster, TcpEventBus, run_tcp_server};
-use tracing::{error, info};
+use tracing::{error, info, warn};
 
 #[tokio::main]
 async fn main() -> Result<()> {
@@ -40,6 +41,15 @@ async fn main() -> Result<()> {
     let auth = Arc::new(JwtAuthService::new(auth_config));
     let hasher = Arc::new(Argon2Hasher);
 
+    match config_store.load_widget_states().await {
+        Ok(states) if !states.is_empty() => {
+            info!(count = states.len(), "loaded cached widget states");
+            projection.seed(states).await;
+        }
+        Ok(_) => {}
+        Err(e) => warn!(error = %e, "failed to load cached widget states"),
+    }
+
     let tcp_addr = cfg.tcp_addr.clone();
     let tcp_bc = broadcaster.clone();
     let tcp_tracker = tracker.clone();