Add websocket handler on server, connect from client

Additionally add /test handler that triggers server->client WS message

server/src/ws.rs

@@ -0,0 +1,32 @@
+use std::{collections::HashMap, net::SocketAddr};
+
+use axum::extract::ws::{Message, WebSocket};
+use letterbox_shared::WebsocketMessage;
+use tracing::{info, warn};
+
+#[derive(Default)]
+pub struct ConnectionTracker {
+    peers: HashMap<SocketAddr, WebSocket>,
+}
+
+impl ConnectionTracker {
+    pub fn add_peer(&mut self, socket: WebSocket, who: SocketAddr) {
+        warn!("adding {who:?} to connection tracker");
+        self.peers.insert(who, socket);
+    }
+    pub async fn send_message_all(&mut self, msg: WebsocketMessage) {
+        let m = serde_json::to_string(&msg).expect("failed to json encode WebsocketMessage");
+        let mut bad_peers = Vec::new();
+        for (who, socket) in &mut self.peers.iter_mut() {
+            if let Err(e) = socket.send(Message::Text(m.clone().into())).await {
+                warn!("{:?} is bad, scheduling for removal: {e}", who);
+                bad_peers.push(who.clone());
+            }
+        }
+
+        for b in bad_peers {
+            info!("removing bad peer {b:?}");
+            self.peers.remove(&b);
+        }
+    }
+}