Move site content between installations as a package

System now exports a content package and imports one, by upload or from
var/pakete. Pages with their revisions, areas, menus, media, forms,
redirects, terms, translations, design and settings are replaced;
submissions, statistics, tasks, plugin state and service keys stay, and
accounts only come along when that is chosen explicitly. A backup comes
first, the site is in maintenance meanwhile, and every file and document
in the package is checked before anything is written.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/Command/PackageImportCommand.php

@@ -0,0 +1,43 @@
+<?php
+
+namespace App\Command;
+
+use App\Ops\SitePackage;
+use Symfony\Component\Console\Attribute\AsCommand;
+use Symfony\Component\Console\Command\Command;
+use Symfony\Component\Console\Input\InputArgument;
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Input\InputOption;
+use Symfony\Component\Console\Output\OutputInterface;
+use Symfony\Component\Console\Style\SymfonyStyle;
+
+#[AsCommand(name: 'cms:paket:import', description: 'Replaces the content of this installation with a content package; accounts stay unless --mit-benutzern (ADR 118).')]
+final class PackageImportCommand extends Command
+{
+    public function __construct(private SitePackage $packages)
+    {
+        parent::__construct();
+    }
+
+    protected function configure(): void
+    {
+        $this->addArgument('datei', InputArgument::REQUIRED, 'Die Zip-Datei des Pakets.')
+            ->addOption('mit-benutzern', null, InputOption::VALUE_NONE, 'Konten und Passwörter aus dem Paket übernehmen.')
+            ->addOption('ja', null, InputOption::VALUE_NONE, 'Ohne Rückfrage ersetzen.');
+    }
+
+    protected function execute(InputInterface $input, OutputInterface $output): int
+    {
+        $io = new SymfonyStyle($input, $output);
+        $file = (string) $input->getArgument('datei');
+        if (!$input->getOption('ja') && !$io->confirm('Die Inhalte dieser Installation werden ersetzt (vorher wird gesichert). Weiter?', false)) {
+            return Command::FAILURE;
+        }
+        $result = $this->packages->import($file, (bool) $input->getOption('mit-benutzern'));
+        foreach ($result['steps'] as $step) {
+            $io->writeln(sprintf('%s %s: %s', $step['ok'] ? 'ok    ' : 'FEHLER', $step['step'], $step['detail']));
+        }
+
+        return $result['ok'] ? Command::SUCCESS : Command::FAILURE;
+    }
+}