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

dashboard/src/ui/widgets/system.rs

@@ -44,9 +44,9 @@ pub struct SystemWidget {
     storage_pools: Vec<StoragePool>,
     
     // Backup metrics
-    backup_repositories: Vec<String>,
-    backup_repository_status: Status,
-    backup_disks: Vec<cm_dashboard_shared::BackupDiskData>,
+    backup_last_time: Option<String>,
+    backup_status: Status,
+    backup_repositories: Vec<cm_dashboard_shared::BackupRepositoryData>,
     
     // Overall status
     has_data: bool,
@@ -112,9 +112,9 @@ impl SystemWidget {
             tmp_status: Status::Unknown,
             tmpfs_mounts: Vec::new(),
             storage_pools: Vec::new(),
+            backup_last_time: None,
+            backup_status: Status::Unknown,
             backup_repositories: Vec::new(),
-            backup_repository_status: Status::Unknown,
-            backup_disks: Vec::new(),
             has_data: false,
             scroll_offset: 0,
             last_viewport_height: 0,
@@ -221,9 +221,9 @@ impl Widget for SystemWidget {
 
         // Extract backup data
         let backup = &agent_data.backup;
+        self.backup_last_time = backup.last_backup_time.clone();
+        self.backup_status = backup.backup_status;
         self.backup_repositories = backup.repositories.clone();
-        self.backup_repository_status = backup.repository_status;
-        self.backup_disks = backup.disks.clone();
 
         // Clamp scroll offset to valid range after update
         // This prevents scroll issues when switching between hosts
@@ -533,79 +533,41 @@ impl SystemWidget {
     fn render_backup(&self) -> Vec<Line<'_>> {
         let mut lines = Vec::new();
 
-        // First section: Repository status and list
-        if !self.backup_repositories.is_empty() {
-            let repo_text = format!("Repo: {}", self.backup_repositories.len());
-            let repo_spans = StatusIcons::create_status_spans(self.backup_repository_status, &repo_text);
-            lines.push(Line::from(repo_spans));
-
-            // List all repositories (sorted for consistent display)
-            let mut sorted_repos = self.backup_repositories.clone();
-            sorted_repos.sort();
-            let repo_count = sorted_repos.len();
-            for (idx, repo) in sorted_repos.iter().enumerate() {
-                let tree_char = if idx == repo_count - 1 { "└─" } else { "├─" };
-                lines.push(Line::from(vec![
-                    Span::styled(format!("  {} ", tree_char), Typography::tree()),
-                    Span::styled(repo.clone(), Typography::secondary()),
-                ]));
-            }
+        if self.backup_repositories.is_empty() {
+            return lines;
         }
 
-        // Second section: Per-disk backup information (sorted by serial for consistent display)
-        let mut sorted_disks = self.backup_disks.clone();
-        sorted_disks.sort_by(|a, b| a.serial.cmp(&b.serial));
-        for disk in &sorted_disks {
-            let truncated_serial = truncate_serial(&disk.serial);
-            let mut details = Vec::new();
+        // Format backup time (use complete timestamp)
+        let time_display = if let Some(ref time_str) = self.backup_last_time {
+            time_str.clone()
+        } else {
+            "unknown".to_string()
+        };
 
-            if let Some(temp) = disk.temperature_celsius {
-                details.push(format!("T: {}°C", temp as i32));
-            }
-            if let Some(wear) = disk.wear_percent {
-                details.push(format!("W: {}%", wear as i32));
-            }
+        // Header: "Repo <complete timestamp>"
+        let repo_text = format!("Repo {}", time_display);
+        let repo_spans = StatusIcons::create_status_spans(self.backup_status, &repo_text);
+        lines.push(Line::from(repo_spans));
 
-            let disk_text = if !details.is_empty() {
-                format!("{} {}", truncated_serial, details.join(" "))
+        // List all repositories with archive count and size
+        let repo_count = self.backup_repositories.len();
+        for (idx, repo) in self.backup_repositories.iter().enumerate() {
+            let tree_char = if idx == repo_count - 1 { "└─" } else { "├─" };
+
+            // Format size: use MB for < 1GB, otherwise GB
+            let size_display = if repo.repo_size_gb < 1.0 {
+                format!("{:.0}MB", repo.repo_size_gb * 1024.0)
             } else {
-                truncated_serial
+                format!("{:.1}GB", repo.repo_size_gb)
             };
 
-            // Overall disk status (worst of backup and usage)
-            let disk_status = disk.backup_status.max(disk.usage_status);
-            let disk_spans = StatusIcons::create_status_spans(disk_status, &disk_text);
-            lines.push(Line::from(disk_spans));
+            let repo_text = format!("{} ({}) {}", repo.name, repo.archive_count, size_display);
 
-            // Show backup time with status
-            if let Some(backup_time) = &disk.last_backup_time {
-                let time_text = format!("Backup: {}", backup_time);
-                let mut time_spans = vec![
-                    Span::styled("  ├─ ", Typography::tree()),
-                ];
-                time_spans.extend(StatusIcons::create_status_spans(disk.backup_status, &time_text));
-                lines.push(Line::from(time_spans));
-            }
-
-            // Show usage with status and archive count
-            let archive_display = if disk.archives_min == disk.archives_max {
-                format!("{}", disk.archives_min)
-            } else {
-                format!("{}-{}", disk.archives_min, disk.archives_max)
-            };
-
-            let usage_text = format!(
-                "Usage: ({}) {:.0}% {:.0}GB/{:.0}GB",
-                archive_display,
-                disk.disk_usage_percent,
-                disk.disk_used_gb,
-                disk.disk_total_gb
-            );
-            let mut usage_spans = vec![
-                Span::styled("  └─ ", Typography::tree()),
+            let mut repo_spans = vec![
+                Span::styled(format!("  {} ", tree_char), Typography::tree()),
             ];
-            usage_spans.extend(StatusIcons::create_status_spans(disk.usage_status, &usage_text));
-            lines.push(Line::from(usage_spans));
+            repo_spans.extend(StatusIcons::create_status_spans(repo.status, &repo_text));
+            lines.push(Line::from(repo_spans));
         }
 
         lines
@@ -876,13 +838,10 @@ impl SystemWidget {
         }
 
         // Backup section
-        if !self.backup_repositories.is_empty() || !self.backup_disks.is_empty() {
-            count += 1; // Header
-            if !self.backup_repositories.is_empty() {
-                count += 1; // Repo header
-                count += self.backup_repositories.len();
-            }
-            count += self.backup_disks.len() * 3; // Each disk has 3 lines
+        if !self.backup_repositories.is_empty() {
+            count += 1; // Header: "Backup:"
+            count += 1; // Repo count and timestamp header
+            count += self.backup_repositories.len(); // Individual repos
         }
 
         count
@@ -988,7 +947,7 @@ impl SystemWidget {
         lines.extend(storage_lines);
 
         // Backup section (if available)
-        if !self.backup_repositories.is_empty() || !self.backup_disks.is_empty() {
+        if !self.backup_repositories.is_empty() {
             lines.push(Line::from(vec![
                 Span::styled("Backup:", Typography::widget_title())
             ]));