feat(agent): service systemd DynamicUser + documentation déploiement

- Ajoute deploy/nanometrics-agent.service avec DynamicUser, ProtectSystem,
  PrivateTmp, NoNewPrivileges et RestrictAddressFamilies
- Ajoute deploy/README.md avec procédure d'installation/désinstallation
- Corrige 3 avertissements clippy : iter_kv_map (network.rs) et
  collapsible_match (mqtt.rs)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

agent/src/metrics/network.rs

@@ -1,8 +1,8 @@
 use sysinfo::Networks;
 
 pub fn get(networks: &Networks) -> (u64, u64) {
-    let rx: u64 = networks.iter().map(|(_, n)| n.total_received()).sum();
-    let tx: u64 = networks.iter().map(|(_, n)| n.total_transmitted()).sum();
+    let rx: u64 = networks.values().map(|n| n.total_received()).sum();
+    let tx: u64 = networks.values().map(|n| n.total_transmitted()).sum();
     (rx, tx)
 }
 

agent/src/transport/mqtt.rs

@@ -57,12 +57,10 @@ pub fn start(
                         QoS::AtLeastOnce,
                     );
                 }
-                Ok(Event::Incoming(Packet::Publish(p))) => {
-                    if p.topic == config_topic_clone {
-                        let _ = incoming_tx.send(MqttIncoming::ConfigUpdate(
-                            p.payload.to_vec(),
-                        ));
-                    }
+                Ok(Event::Incoming(Packet::Publish(p))) if p.topic == config_topic_clone => {
+                    let _ = incoming_tx.send(MqttIncoming::ConfigUpdate(
+                        p.payload.to_vec(),
+                    ));
                 }
                 Err(e) => {
                     eprintln!("[mqtt] erreur: {}", e);