feat(backup): add containerarchive-backed backup storage, restore, download, and pruning support

ts/classes/onebox.ts

@@ -192,6 +192,14 @@ export class Onebox {
       // Start auto-update monitoring for registry services
       this.services.startAutoUpdateMonitoring();
 
+      // Initialize BackupManager (containerarchive repository, non-critical)
+      try {
+        await this.backupManager.init();
+      } catch (error) {
+        logger.warn('BackupManager initialization failed - backups will be limited');
+        logger.warn(`Error: ${getErrorMessage(error)}`);
+      }
+
       // Initialize Backup Scheduler (non-critical)
       try {
         await this.backupScheduler.init();
@@ -430,6 +438,9 @@ export class Onebox {
       // Stop Caddy log receiver
       await this.caddyLogReceiver.stop();
 
+      // Close backup archive
+      await this.backupManager.close();
+
       // Close database
       this.database.close();