Add network interface collection and display

Extend NixOS collector to gather network interfaces using ip command JSON output. Display all interfaces with IPv4 and IPv6 addresses in Network section above CPU metrics. Filters out loopback and link-local addresses.

Version bump to 0.1.161

shared/src/agent_data.rs

@@ -16,11 +16,26 @@ pub struct AgentData {
 /// System-level monitoring data
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct SystemData {
+    pub network: NetworkData,
     pub cpu: CpuData,
     pub memory: MemoryData,
     pub storage: StorageData,
 }
 
+/// Network interface monitoring data
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct NetworkData {
+    pub interfaces: Vec<NetworkInterfaceData>,
+}
+
+/// Individual network interface data
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct NetworkInterfaceData {
+    pub name: String,
+    pub ipv4_addresses: Vec<String>,
+    pub ipv6_addresses: Vec<String>,
+}
+
 /// CPU monitoring data
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct CpuData {
@@ -171,6 +186,9 @@ impl AgentData {
             build_version: None,
             timestamp: chrono::Utc::now().timestamp() as u64,
             system: SystemData {
+                network: NetworkData {
+                    interfaces: Vec::new(),
+                },
                 cpu: CpuData {
                     load_1min: 0.0,
                     load_5min: 0.0,