v0.2.0 (10/N): bridge:export console command + QML hook

PLAN.md §12 *Data backup / export* called for "a bridge:export console
command and a UI hook for backup-to-file from v1". Shipping both now
so the v0.2.0 surface has the data-portability story end-to-end:

PHP side — `bin/console bridge:export <destination>`:
- Reads the source path from DATABASE_URL so it works in dev mode
  (developer's source-tree var/data.sqlite) and bundled mode (user
  data dir SQLite) without environment-aware logic.
- SQLite-only by design (PLAN.md §6 — single-instance SQLite-first);
  emits a clear error for non-sqlite:// URLs rather than pretending
  to support drivers that need driver-specific dump tooling.
- Overwrites the destination if it exists (the FileDialog or shell
  redirect that produced the path has already confirmed).
- 4 unit tests: happy path, non-SQLite URL, missing source,
  overwrite. Test count 24 → 28.

QML side — Q_INVOKABLE BackendConnection.exportDatabase(path):
- Bundled mode only; dev mode emits databaseExportFailed and
  returns false (developers own their SQLite directly).
- Accepts both filesystem paths and `file://` URLs (FileDialog
  results).
- Returns synchronously with bool but also emits async signals
  databaseExported(dst) / databaseExportFailed(reason) so QML
  can drive a snackbar / log without polling the return value.
- Removes any existing destination first (QFile::copy refuses
  to overwrite); the picker has already confirmed the choice.

Drive-by: parse_url() rejects sqlite:///abs/path on PHP 8.5+ (the
host-less triple-slash trips its strictness). Switched to a
prefix-strip — Doctrine DBAL only emits two URL shapes for
SQLite anyway (sqlite:///abs and sqlite://relative).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

framework/php/tests/Command/BridgeExportCommandTest.php

@@ -0,0 +1,82 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PhpQml\Bridge\Tests\Command;
+
+use PhpQml\Bridge\Command\BridgeExportCommand;
+use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\TestCase;
+use Symfony\Component\Console\Tester\CommandTester;
+
+#[CoversClass(BridgeExportCommand::class)]
+final class BridgeExportCommandTest extends TestCase
+{
+    private string $tmpDir = '';
+
+    protected function setUp(): void
+    {
+        $this->tmpDir = sys_get_temp_dir().'/bridge-export-test-'.uniqid();
+        mkdir($this->tmpDir, 0o700, true);
+    }
+
+    protected function tearDown(): void
+    {
+        // Brutal but adequate for a flat test dir.
+        foreach (glob($this->tmpDir.'/*') ?: [] as $f) {
+            @unlink($f);
+        }
+        @rmdir($this->tmpDir);
+    }
+
+    public function testCopiesSqliteFileToDestination(): void
+    {
+        $source = $this->tmpDir.'/source.sqlite';
+        file_put_contents($source, 'fake-sqlite-bytes');
+
+        $tester      = new CommandTester(new BridgeExportCommand("sqlite:///{$source}"));
+        $destination = $this->tmpDir.'/exported.sqlite';
+
+        $exitCode = $tester->execute(['destination' => $destination]);
+
+        self::assertSame(0, $exitCode);
+        self::assertFileExists($destination);
+        self::assertSame('fake-sqlite-bytes', file_get_contents($destination));
+        self::assertStringContainsString('Exported', $tester->getDisplay());
+    }
+
+    public function testFailsForNonSqliteUrl(): void
+    {
+        $tester = new CommandTester(new BridgeExportCommand('postgres://user@host/db'));
+
+        $exitCode = $tester->execute(['destination' => $this->tmpDir.'/x.sqlite']);
+
+        self::assertSame(1, $exitCode);
+        self::assertStringContainsString('not a sqlite:/// URL', $tester->getDisplay());
+    }
+
+    public function testFailsWhenSourceMissing(): void
+    {
+        $tester = new CommandTester(new BridgeExportCommand("sqlite:///{$this->tmpDir}/no-such.sqlite"));
+
+        $exitCode = $tester->execute(['destination' => $this->tmpDir.'/x.sqlite']);
+
+        self::assertSame(1, $exitCode);
+        self::assertStringContainsString('does not exist', $tester->getDisplay());
+    }
+
+    public function testOverwritesExistingDestination(): void
+    {
+        $source = $this->tmpDir.'/source.sqlite';
+        file_put_contents($source, 'new-bytes');
+
+        $destination = $this->tmpDir.'/exported.sqlite';
+        file_put_contents($destination, 'old-bytes');
+
+        $tester   = new CommandTester(new BridgeExportCommand("sqlite:///{$source}"));
+        $exitCode = $tester->execute(['destination' => $destination]);
+
+        self::assertSame(0, $exitCode);
+        self::assertSame('new-bytes', file_get_contents($destination));
+    }
+}