feat(agent): payload AgentMetrics + SmartMetrics + tests

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

agent/tests/payload_test.rs

@@ -0,0 +1,56 @@
+use nanometrics_agent::payload::{AgentMetrics, SmartMetrics};
+
+#[test]
+fn test_serialize_json_complet() {
+    let m = AgentMetrics {
+        hostname: "srv-01".to_string(),
+        ip: "10.0.0.11".to_string(),
+        cpu_percent: Some(42.5),
+        memory_used: Some(3_000_000_000),
+        memory_free: Some(5_000_000_000),
+        memory_total: Some(8_000_000_000),
+        hdd_used: Some(60_000_000_000),
+        hdd_free: Some(140_000_000_000),
+        hdd_total: Some(200_000_000_000),
+        uptime: Some(1234567),
+        network_rx: Some(1024),
+        network_tx: Some(512),
+        temperature: None,
+        smart: None,
+        status: "online".to_string(),
+    };
+    let json = serde_json::to_string(&m).unwrap();
+    assert!(json.contains("\"hostname\":\"srv-01\""));
+    assert!(json.contains("\"cpu_percent\":42.5"));
+    assert!(json.contains("\"status\":\"online\""));
+    assert!(json.contains("\"temperature\":null"));
+}
+
+#[test]
+fn test_serialize_avec_smart() {
+    let m = AgentMetrics {
+        hostname: "srv-01".to_string(),
+        ip: "10.0.0.11".to_string(),
+        smart: Some(SmartMetrics {
+            passed: true,
+            temperature: Some(34),
+            reallocated_sectors: Some(0),
+            power_on_hours: Some(4213),
+            wear_level: Some(98),
+        }),
+        status: "online".to_string(),
+        ..Default::default()
+    };
+    let json = serde_json::to_string(&m).unwrap();
+    assert!(json.contains("\"passed\":true"));
+    assert!(json.contains("\"temperature\":34"));
+}
+
+#[test]
+fn test_deserialize_depuis_json() {
+    let json = r#"{"hostname":"host1","ip":"10.0.0.1","status":"online","cpu_percent":55.0,"memory_used":null,"memory_free":null,"memory_total":null,"hdd_used":null,"hdd_free":null,"hdd_total":null,"uptime":null,"network_rx":null,"network_tx":null,"temperature":null,"smart":null}"#;
+    let m: AgentMetrics = serde_json::from_str(json).unwrap();
+    assert_eq!(m.hostname, "host1");
+    assert_eq!(m.cpu_percent, Some(55.0));
+    assert!(m.smart.is_none());
+}