feat(backup): Add backup system: BackupManager, DB schema, API endpoints and UI support

Introduce a complete service backup/restore subsystem with encrypted archives, database records and REST endpoints. Implements BackupManager with export/import for service config, platform resources (MongoDB, MinIO, ClickHouse), and Docker images; adds BackupRepository and migrations for backups table and include_image_in_backup; integrates backup flows into the HTTP API and the UI client; exposes backup password management and restore modes (restore/import/clone). Wire BackupManager into Onebox initialization.

ts/classes/onebox.ts

@@ -20,6 +20,7 @@ import { CertRequirementManager } from './cert-requirement-manager.ts';
 import { RegistryManager } from './registry.ts';
 import { PlatformServicesManager } from './platform-services/index.ts';
 import { CaddyLogReceiver } from './caddy-log-receiver.ts';
+import { BackupManager } from './backup-manager.ts';
 
 export class Onebox {
   public database: OneboxDatabase;
@@ -36,6 +37,7 @@ export class Onebox {
   public registry: RegistryManager;
   public platformServices: PlatformServicesManager;
   public caddyLogReceiver: CaddyLogReceiver;
+  public backupManager: BackupManager;
 
   private initialized = false;
 
@@ -67,6 +69,9 @@ export class Onebox {
 
     // Initialize Caddy log receiver
     this.caddyLogReceiver = new CaddyLogReceiver(9999);
+
+    // Initialize Backup manager
+    this.backupManager = new BackupManager(this);
   }
 
   /**