fix(tenant): route runtime traffic to tenant databases

Wire Doctrine's default connection to the tenant database resolved from the subdomain for HTTP requests and tenant-scoped Messenger messages while keeping master-only services on the master connection.

This removes the production inconsistency where demo data, migrations and tenant commands used the tenant database but the web runtime still read from master.

backend/tests/Unit/Shared/Infrastructure/Messenger/TenantMessageTenantIdResolverTest.php

@@ -0,0 +1,57 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Tests\Unit\Shared\Infrastructure\Messenger;
+
+use App\Shared\Domain\Tenant\TenantId;
+use App\Shared\Infrastructure\Messenger\TenantMessageTenantIdResolver;
+use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\Test;
+use PHPUnit\Framework\TestCase;
+
+#[CoversClass(TenantMessageTenantIdResolver::class)]
+final class TenantMessageTenantIdResolverTest extends TestCase
+{
+    #[Test]
+    public function itReadsTenantIdsFromStringProperties(): void
+    {
+        $resolver = new TenantMessageTenantIdResolver();
+        $message = new readonly class('a1b2c3d4-e5f6-7890-abcd-ef1234567890') {
+            public function __construct(
+                public string $tenantId,
+            ) {
+            }
+        };
+
+        self::assertSame('a1b2c3d4-e5f6-7890-abcd-ef1234567890', $resolver->resolve($message));
+    }
+
+    #[Test]
+    public function itReadsTenantIdsFromValueObjects(): void
+    {
+        $resolver = new TenantMessageTenantIdResolver();
+        $message = new readonly class(TenantId::fromString('b2c3d4e5-f6a7-8901-bcde-f12345678901')) {
+            public function __construct(
+                public TenantId $tenantId,
+            ) {
+            }
+        };
+
+        self::assertSame('b2c3d4e5-f6a7-8901-bcde-f12345678901', $resolver->resolve($message));
+    }
+
+    #[Test]
+    public function itReturnsNullWhenTheMessageIsNotTenantScoped(): void
+    {
+        $resolver = new TenantMessageTenantIdResolver();
+        $message = new readonly class('') {
+            public function __construct(
+                public string $batchId,
+            ) {
+            }
+        };
+
+        self::assertNull($resolver->resolve($message));
+    }
+}