User restore by user id, backup:user:list (#22)

backup:user:restore <location> <uid> only said "is not a recorded user export": the argument
is the manifest path, which only backup:user:backup printed once. backup:user:list shows the
exports again; a bare user id works when that user has exactly one export, otherwise the error
lists them. The export is resolved before the replace confirmation.

Fixes #22

lib/Command/ListUserExports.php

@@ -0,0 +1,64 @@
+<?php
+
+declare(strict_types=1);
+
+// SPDX-FileCopyrightText: 2026 Dillard Blom
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+namespace OCA\NgBackup\Command;
+
+use OCA\NgBackup\Service\TargetService;
+use Symfony\Component\Console\Command\Command;
+use Symfony\Component\Console\Helper\Table;
+use Symfony\Component\Console\Input\InputArgument;
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Output\OutputInterface;
+
+final class ListUserExports extends Command {
+	public function __construct(
+		private TargetService $targets,
+	) {
+		parent::__construct();
+	}
+
+	protected function configure(): void {
+		$this->setName('backup:user:list')
+			->setDescription('List the user exports (backup:user:backup) on a location')
+			->addArgument('target', InputArgument::OPTIONAL, 'Location name or id (default: all)')
+			->addArgument('user', InputArgument::OPTIONAL, 'Only the exports of this user id')
+			->setHelp(<<<'HELP'
+The manifest column is what occ backup:user:restore expects. A safety export made by a restore
+with --mode=replace is listed here as well.
+
+Example:
+  occ backup:user:list offsite alice
+HELP);
+	}
+
+	protected function execute(InputInterface $input, OutputInterface $output): int {
+		$name = $input->getArgument('target');
+		$uid = $input->getArgument('user');
+		$rows = [];
+		try {
+			$targets = $name === null ? $this->targets->list() : [$this->targets->get($name)];
+			foreach ($targets as $t) {
+				foreach ($this->targets->repository($t)->listUserExports($uid) as $path) {
+					$parts = explode('/', $path, 3);
+					$user = $parts[1] ?? '';
+					$exportId = $parts[2] ?? '';
+					$time = \DateTimeImmutable::createFromFormat('Ymd\THis\Z', substr($exportId, 0, 16), new \DateTimeZone('UTC'));
+					$rows[] = [$t->getName(), $user, $time !== false ? $time->format('Y-m-d H:i') : '', $path];
+				}
+			}
+		} catch (\Throwable $e) {
+			$output->writeln('<error>' . $e->getMessage() . '</error>');
+			return 1;
+		}
+		if ($rows === []) {
+			$output->writeln('No user exports yet (occ backup:user:backup).');
+			return 0;
+		}
+		(new Table($output))->setHeaders(['location', 'user', 'date (UTC)', 'manifest'])->setRows($rows)->render();
+		return 0;
+	}
+}