Fix service status icon mismatch with single source of truth architecture

- Remove duplicate status string fields from ServiceData and SubServiceData
- Use only Status enum as single source of truth for service status
- Agent calculates Status enum using calculate_service_status()
- Dashboard converts Status enum to display text for UI
- Implement flexible metrics system for sub-services with label/value/unit
- Fix status icon/text mismatches (inactive services now show gray circles)
- Ensure perfect alignment between service icons and status text

shared/src/agent_data.rs

@@ -111,11 +111,27 @@ pub struct PoolDriveData {
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct ServiceData {
     pub name: String,
-    pub status: String, // "active", "inactive", "failed"
     pub memory_mb: f32,
     pub disk_gb: f32,
     pub user_stopped: bool,
     pub service_status: Status,
+    pub sub_services: Vec<SubServiceData>,
+}
+
+/// Sub-service data (nginx sites, docker containers, etc.)
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct SubServiceData {
+    pub name: String,
+    pub service_status: Status,
+    pub metrics: Vec<SubServiceMetric>,
+}
+
+/// Individual metric for a sub-service
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct SubServiceMetric {
+    pub label: String,
+    pub value: f32,
+    pub unit: Option<String>,
 }
 
 /// Backup system data