Add connected technician tracking to dashboard

- Add ViewerInfo struct to track viewer name and connection time
- Update session manager to track viewers with names
- Update API to return viewer list for each session
- Update dashboard to display "Mike Connected (3 min)" on machine bars
- Update viewer.html to pass viewer_name parameter

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

server/src/relay/mod.rs

@@ -34,6 +34,12 @@ pub struct AgentParams {
 #[derive(Debug, Deserialize)]
 pub struct ViewerParams {
     session_id: String,
+    #[serde(default = "default_viewer_name")]
+    viewer_name: String,
+}
+
+fn default_viewer_name() -> String {
+    "Technician".to_string()
 }
 
 /// WebSocket handler for agent connections
@@ -58,9 +64,10 @@ pub async fn viewer_ws_handler(
     Query(params): Query<ViewerParams>,
 ) -> impl IntoResponse {
     let session_id = params.session_id;
+    let viewer_name = params.viewer_name;
     let sessions = state.sessions.clone();
 
-    ws.on_upgrade(move |socket| handle_viewer_connection(socket, sessions, session_id))
+    ws.on_upgrade(move |socket| handle_viewer_connection(socket, sessions, session_id, viewer_name))
 }
 
 /// Handle an agent WebSocket connection
@@ -242,6 +249,7 @@ async fn handle_viewer_connection(
     socket: WebSocket,
     sessions: SessionManager,
     session_id_str: String,
+    viewer_name: String,
 ) {
     // Parse session ID
     let session_id = match uuid::Uuid::parse_str(&session_id_str) {
@@ -256,7 +264,7 @@ async fn handle_viewer_connection(
     let viewer_id = Uuid::new_v4().to_string();
 
     // Join the session (this sends StartStream to agent if first viewer)
-    let (mut frame_rx, input_tx) = match sessions.join_session(session_id, viewer_id.clone()).await {
+    let (mut frame_rx, input_tx) = match sessions.join_session(session_id, viewer_id.clone(), viewer_name.clone()).await {
         Some(channels) => channels,
         None => {
             warn!("Session not found: {}", session_id);
@@ -264,7 +272,7 @@ async fn handle_viewer_connection(
         }
     };
 
-    info!("Viewer {} joined session: {}", viewer_id, session_id);
+    info!("Viewer {} ({}) joined session: {}", viewer_name, viewer_id, session_id);
 
     let (mut ws_sender, mut ws_receiver) = socket.split();