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/api/mod.rs

@@ -9,6 +9,24 @@ use uuid::Uuid;
 
 use crate::session::SessionManager;
 
+/// Viewer info returned by API
+#[derive(Debug, Serialize)]
+pub struct ViewerInfoApi {
+    pub id: String,
+    pub name: String,
+    pub connected_at: String,
+}
+
+impl From<crate::session::ViewerInfo> for ViewerInfoApi {
+    fn from(v: crate::session::ViewerInfo) -> Self {
+        Self {
+            id: v.id,
+            name: v.name,
+            connected_at: v.connected_at.to_rfc3339(),
+        }
+    }
+}
+
 /// Session info returned by API
 #[derive(Debug, Serialize)]
 pub struct SessionInfo {
@@ -17,6 +35,7 @@ pub struct SessionInfo {
     pub agent_name: String,
     pub started_at: String,
     pub viewer_count: usize,
+    pub viewers: Vec<ViewerInfoApi>,
     pub is_streaming: bool,
     pub is_online: bool,
     pub is_persistent: bool,
@@ -35,6 +54,7 @@ impl From<crate::session::Session> for SessionInfo {
             agent_name: s.agent_name,
             started_at: s.started_at.to_rfc3339(),
             viewer_count: s.viewer_count,
+            viewers: s.viewers.into_iter().map(ViewerInfoApi::from).collect(),
             is_streaming: s.is_streaming,
             is_online: s.is_online,
             is_persistent: s.is_persistent,