Integrate backup metrics into system widget with enhanced disk monitoring

Replace standalone backup widget with compact backup section in system widget displaying disk serial, temperature, wear level, timing, and usage information.

Changes:
- Remove standalone backup widget and integrate into system widget
- Update backup collector to read TOML format from backup script
- Add BackupDiskData structure with serial, usage, temperature, wear fields
- Implement compact backup display matching specification format
- Add time formatting utilities for backup timing display
- Update backup data extraction from TOML with disk space parsing

Version bump to v0.1.149

shared/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "cm-dashboard-shared"
-version = "0.1.148"
+version = "0.1.149"
 edition = "2021"
 
 [dependencies]

shared/src/agent_data.rs

@@ -142,6 +142,19 @@ pub struct BackupData {
     pub next_scheduled: Option<u64>,
     pub total_size_gb: Option<f32>,
     pub repository_health: Option<String>,
+    pub repository_disk: Option<BackupDiskData>,
+    pub last_backup_size_gb: Option<f32>,
+}
+
+/// Backup repository disk information
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct BackupDiskData {
+    pub serial: String,
+    pub usage_percent: f32,
+    pub used_gb: f32,
+    pub total_gb: f32,
+    pub wear_percent: Option<f32>,
+    pub temperature_celsius: Option<f32>,
 }
 
 impl AgentData {
@@ -184,6 +197,8 @@ impl AgentData {
                 next_scheduled: None,
                 total_size_gb: None,
                 repository_health: None,
+                repository_disk: None,
+                last_backup_size_gb: None,
             },
         }
     }