Restructure backup display to show per-repository metrics

Remove disk-based backup display and implement repository-centric view
with per-repo archive counts and sizes. Backup now uses NFS storage
instead of direct disk monitoring.

Changes:
- Remove BackupDiskData, add BackupRepositoryData structure
- Display format: "Repo <timestamp>" with per-repo details
- Show archive count and size (MB/GB) for each repository
- Agent aggregates repo data from backup status TOML files
- Dashboard renders repo list with individual status indicators

shared/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "cm-dashboard-shared"
-version = "0.1.266"
+version = "0.1.267"
 edition = "2021"
 
 [dependencies]

shared/src/agent_data.rs

@@ -182,27 +182,18 @@ pub struct SubServiceMetric {
 /// Backup system data
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct BackupData {
-    pub repositories: Vec<String>,
-    pub repository_status: Status,
-    pub disks: Vec<BackupDiskData>,
-}
-
-/// Backup repository disk information
-#[derive(Debug, Clone, Serialize, Deserialize)]
-pub struct BackupDiskData {
-    pub serial: String,
-    pub product_name: Option<String>,
-    pub wear_percent: Option<f32>,
-    pub temperature_celsius: Option<f32>,
     pub last_backup_time: Option<String>,
     pub backup_status: Status,
-    pub disk_usage_percent: f32,
-    pub disk_used_gb: f32,
-    pub disk_total_gb: f32,
-    pub usage_status: Status,
-    pub services: Vec<String>,
-    pub archives_min: i64,
-    pub archives_max: i64,
+    pub repositories: Vec<BackupRepositoryData>,
+}
+
+/// Individual backup repository information
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct BackupRepositoryData {
+    pub name: String,
+    pub archive_count: i64,
+    pub repo_size_gb: f32,
+    pub status: Status,
 }
 
 impl AgentData {
@@ -245,9 +236,9 @@ impl AgentData {
             },
             services: Vec::new(),
             backup: BackupData {
+                last_backup_time: None,
+                backup_status: Status::Unknown,
                 repositories: Vec::new(),
-                repository_status: Status::Unknown,
-                disks: Vec::new(),
             },
         }
     }