Add ZMQ communication statistics tracking and display

dashboard/src/ui/widgets/system.rs

@@ -15,6 +15,10 @@ pub struct SystemWidget {
     nixos_build: Option<String>,
     agent_hash: Option<String>,
 
+    // ZMQ communication stats
+    zmq_packets_received: Option<u64>,
+    zmq_last_packet_age: Option<f64>,
+
     // Network interfaces
     network_interfaces: Vec<cm_dashboard_shared::NetworkInterfaceData>,
 
@@ -92,6 +96,8 @@ impl SystemWidget {
         Self {
             nixos_build: None,
             agent_hash: None,
+            zmq_packets_received: None,
+            zmq_last_packet_age: None,
             network_interfaces: Vec::new(),
             cpu_load_1min: None,
             cpu_load_5min: None,
@@ -154,6 +160,12 @@ impl SystemWidget {
     pub fn _get_agent_hash(&self) -> Option<&String> {
         self.agent_hash.as_ref()
     }
+
+    /// Update ZMQ communication statistics
+    pub fn update_zmq_stats(&mut self, packets_received: u64, last_packet_age_secs: f64) {
+        self.zmq_packets_received = Some(packets_received);
+        self.zmq_last_packet_age = Some(last_packet_age_secs);
+    }
 }
 
 use super::Widget;
@@ -796,6 +808,18 @@ impl SystemWidget {
             Span::styled(format!("Agent: {}", agent_version_text), Typography::secondary())
         ]));
 
+        // ZMQ communication stats
+        if let (Some(packets), Some(age)) = (self.zmq_packets_received, self.zmq_last_packet_age) {
+            let age_text = if age < 1.0 {
+                format!("{:.0}ms ago", age * 1000.0)
+            } else {
+                format!("{:.1}s ago", age)
+            };
+            lines.push(Line::from(vec![
+                Span::styled(format!("ZMQ: {} pkts, last {}", packets, age_text), Typography::secondary())
+            ]));
+        }
+
         // CPU section
         lines.push(Line::from(vec![
             Span::styled("CPU:", Typography::widget_title())