Implement per-service disk usage monitoring

Replaced system-wide disk usage with accurate per-service tracking by scanning
service-specific directories. Services like sshd now correctly show minimal
disk usage instead of misleading system totals.

- Rename storage widget and add drive capacity/usage columns
- Move host display to main dashboard title for cleaner layout
- Replace separate alert displays with color-coded row highlighting
- Add per-service disk usage collection using du command
- Update services widget formatting to handle small disk values
- Restructure into workspace with dedicated agent and dashboard packages

dashboard/src/data/metrics.rs

@@ -19,6 +19,8 @@ pub struct DriveInfo {
     pub wear_level: f32,
     pub power_on_hours: u64,
     pub available_spare: f32,
+    pub capacity_gb: Option<f32>,
+    pub used_gb: Option<f32>,
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
@@ -44,6 +46,28 @@ pub struct ServiceSummary {
     pub failed: usize,
     pub memory_used_mb: f32,
     pub memory_quota_mb: f32,
+    #[serde(default)]
+    pub system_memory_used_mb: f32,
+    #[serde(default)]
+    pub system_memory_total_mb: f32,
+    #[serde(default)]
+    pub disk_used_gb: f32,
+    #[serde(default)]
+    pub disk_total_gb: f32,
+    #[serde(default)]
+    pub cpu_load_1: f32,
+    #[serde(default)]
+    pub cpu_load_5: f32,
+    #[serde(default)]
+    pub cpu_load_15: f32,
+    #[serde(default)]
+    pub cpu_freq_mhz: Option<f32>,
+    #[serde(default)]
+    pub cpu_temp_c: Option<f32>,
+    #[serde(default)]
+    pub gpu_load_percent: Option<f32>,
+    #[serde(default)]
+    pub gpu_temp_c: Option<f32>,
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
@@ -54,6 +78,8 @@ pub struct ServiceInfo {
     pub memory_quota_mb: f32,
     pub cpu_percent: f32,
     pub sandbox_limit: Option<f32>,
+    #[serde(default)]
+    pub disk_used_gb: f32,
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize)]