Integrate smart collector into metrics manager

- Add SmartCollector import and initialization
- Enable in both normal and benchmark modes
- Fixes infinite smartctl loop issue by properly managing collector
- Smart collector now active when config.smart.enabled = true

agent/src/metrics/mod.rs

@@ -4,7 +4,7 @@ use tracing::{error, info};
 
 use crate::collectors::{
     backup::BackupCollector, cpu::CpuCollector, disk::DiskCollector, memory::MemoryCollector,
-    nixos::NixOSCollector, systemd::SystemdCollector, Collector,
+    nixos::NixOSCollector, smart::SmartCollector, systemd::SystemdCollector, Collector,
 };
 use crate::config::{AgentConfig, CollectorConfig};
 
@@ -61,6 +61,14 @@ impl MetricCollectionManager {
                     info!("BENCHMARK: Backup collector only");
                 }
             }
+            Some("smart") => {
+                // SMART collector only
+                if config.smart.enabled {
+                    let smart_collector = SmartCollector;
+                    collectors.push(Box::new(smart_collector));
+                    info!("BENCHMARK: SMART collector only");
+                }
+            }
             Some("none") => {
                 // No collectors - test agent loop only
                 info!("BENCHMARK: No collectors enabled");
@@ -101,6 +109,12 @@ impl MetricCollectionManager {
                     collectors.push(Box::new(nixos_collector));
                     info!("NixOS collector initialized");
                 }
+
+                if config.smart.enabled {
+                    let smart_collector = SmartCollector;
+                    collectors.push(Box::new(smart_collector));
+                    info!("SMART collector initialized");
+                }
             }
         }