Implement nginx site status monitoring with unreachable detection

- Show 'unreachable' status for nginx sites that fail connection tests
- Set service status to error (red) for unreachable sites
- Display latency in milliseconds for responsive sites
- Properly count failed sites in service summary statistics
- Improve nginx site monitoring reliability and visibility

agent/src/collectors/service.rs

@@ -1358,9 +1358,15 @@ impl Collector for ServiceCollector {
                                 // Measure latency for this site
                                 let latency = self.measure_site_latency(site).await;
                                 
+                                // Determine status and description based on latency measurement
+                                let (site_status, site_description) = match latency {
+                                    Some(ms) => (ServiceStatus::Running, None),
+                                    None => (ServiceStatus::Stopped, Some(vec!["unreachable".to_string()])),
+                                };
+                                
                                 services.push(ServiceData {
                                     name: site.clone(),
-                                    status: ServiceStatus::Running, // Assume sites are running if nginx is running
+                                    status: site_status,
                                     memory_used_mb: 0.0,
                                     memory_quota_mb: 0.0,
                                     cpu_percent: 0.0,
@@ -1369,11 +1375,17 @@ impl Collector for ServiceCollector {
                                     disk_quota_gb: 0.0,
                                     is_sandboxed: false, // Sub-services inherit parent sandbox status
                                     is_sandbox_excluded: false,
-                                    description: None,
+                                    description: site_description,
                                     sub_service: Some("nginx".to_string()),
                                     latency_ms: latency,
                                 });
-                                healthy += 1;
+                                
+                                // Update counters based on site status
+                                match site_status {
+                                    ServiceStatus::Running => healthy += 1,
+                                    ServiceStatus::Stopped => failed += 1,
+                                    _ => degraded += 1,
+                                }
                             }
                         }
                     }