Add Docker backup support: download button, SQLite restore fix, decouple from auto-update

- Decouple backup creation/restore UI from can_auto_update so Docker
  and other non-git installations can use backup features
- Add backup download endpoint for saving backups externally
- Fix SQLite restore to use configured DATABASE_URL path instead of
  hardcoded var/app.db (affects Docker and custom SQLite paths)
- Show Docker-specific warning about var/backups/ not being persisted
- Pass is_docker flag to template via InstallationTypeDetector

src/Controller/UpdateManagerController.php

@@ -24,14 +24,17 @@ declare(strict_types=1);
 namespace App\Controller;
 
 use App\Services\System\BackupManager;
+use App\Services\System\InstallationTypeDetector;
 use App\Services\System\UpdateChecker;
 use App\Services\System\UpdateExecutor;
 use Shivas\VersioningBundle\Service\VersionManagerInterface;
 use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
 use Symfony\Component\DependencyInjection\Attribute\Autowire;
+use Symfony\Component\HttpFoundation\BinaryFileResponse;
 use Symfony\Component\HttpFoundation\JsonResponse;
 use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\HttpFoundation\Response;
+use Symfony\Component\HttpFoundation\ResponseHeaderBag;
 use Symfony\Component\HttpKernel\Exception\AccessDeniedHttpException;
 use Symfony\Component\Routing\Attribute\Route;
 
@@ -49,6 +52,7 @@ class UpdateManagerController extends AbstractController
         private readonly UpdateExecutor $updateExecutor,
         private readonly VersionManagerInterface $versionManager,
         private readonly BackupManager $backupManager,
+        private readonly InstallationTypeDetector $installationTypeDetector,
         #[Autowire(env: 'bool:DISABLE_WEB_UPDATES')]
         private readonly bool $webUpdatesDisabled = false,
         #[Autowire(env: 'bool:DISABLE_BACKUP_RESTORE')]
@@ -101,6 +105,7 @@ class UpdateManagerController extends AbstractController
             'backups' => $this->backupManager->getBackups(),
             'web_updates_disabled' => $this->webUpdatesDisabled,
             'backup_restore_disabled' => $this->backupRestoreDisabled,
+            'is_docker' => $this->installationTypeDetector->isDocker(),
         ]);
     }
 
@@ -388,6 +393,25 @@ class UpdateManagerController extends AbstractController
         return $this->redirectToRoute('admin_update_manager');
     }
 
+    /**
+     * Download a backup file.
+     */
+    #[Route('/backup/download/{filename}', name: 'admin_update_manager_backup_download', methods: ['GET'])]
+    public function downloadBackup(string $filename): BinaryFileResponse
+    {
+        $this->denyAccessUnlessGranted('@system.manage_updates');
+
+        $details = $this->backupManager->getBackupDetails($filename);
+        if (!$details) {
+            throw $this->createNotFoundException('Backup not found');
+        }
+
+        $response = new BinaryFileResponse($details['path']);
+        $response->setContentDisposition(ResponseHeaderBag::DISPOSITION_ATTACHMENT, $details['file']);
+
+        return $response;
+    }
+
     /**
      * Restore from a backup.
      */

src/Services/System/BackupManager.php

@@ -327,14 +327,14 @@ readonly class BackupManager
      */
     private function restoreDatabaseFromBackup(string $tempDir): void
     {
+        // Get database connection params from Doctrine
+        $connection = $this->entityManager->getConnection();
+        $params = $connection->getParams();
+        $platform = $connection->getDatabasePlatform();
+
         // Check for SQL dump (MySQL/PostgreSQL)
         $sqlFile = $tempDir . '/database.sql';
         if (file_exists($sqlFile)) {
-            // Import SQL using mysql/psql command directly
-            // First, get database connection params from Doctrine
-            $connection = $this->entityManager->getConnection();
-            $params = $connection->getParams();
-            $platform = $connection->getDatabasePlatform();
 
             if ($platform instanceof AbstractMySQLPlatform) {
                 // Use mysql command to import - need to use shell to handle input redirection
@@ -403,7 +403,8 @@ readonly class BackupManager
         // Check for SQLite database file
         $sqliteFile = $tempDir . '/var/app.db';
         if (file_exists($sqliteFile)) {
-            $targetDb = $this->projectDir . '/var/app.db';
+            // Use the actual configured SQLite path from Doctrine, not a hardcoded path
+            $targetDb = $params['path'] ?? $this->projectDir . '/var/app.db';
             $this->filesystem->copy($sqliteFile, $targetDb, true);
             return;
         }