Create dedicated network collector with physical/virtual interface grouping

Move network collection from NixOS collector to dedicated NetworkCollector. Add link status detection for physical interfaces (up/down). Group interfaces by physical/virtual, show status icons for physical NICs only. Down interfaces show as Inactive instead of Critical.

Version bump to 0.1.165

shared/src/agent_data.rs

@@ -34,6 +34,9 @@ pub struct NetworkInterfaceData {
     pub name: String,
     pub ipv4_addresses: Vec<String>,
     pub ipv6_addresses: Vec<String>,
+    pub is_physical: bool,
+    pub link_status: Status,
+    pub parent_interface: Option<String>,
 }
 
 /// CPU monitoring data