v0.2.0 (7/N): make:bridge:event maker

Implements PLAN.md §8's third makers-table row. Single-command path
from a PHP domain event to a QML signal-handler:

  - src/Event/<Name>Event.php — readonly value object stub
  - src/EventSubscriber/<Name>Subscriber.php — listens to the event,
    republishes via PublisherInterface on app://event/<kebab-name>
    with op:"event"
  - {qml_path}/<Name>EventHandler.qml — MercureClient bound to the
    topic, re-emits the envelope's data as a typed signal

Stub uses an `array $payload` field so the user can substitute typed
properties for whatever shape they need. Subscriber example uses the
PublisherInterface contract from chunk 1; QML stub uses MercureClient
+ BackendConnection both already shipping.

Wired into services.yaml's when@dev block (autoconfigure picks up
maker.command tag, same pattern as existing BridgeResourceMaker /
BridgeWindowMaker). Three new snapshot baselines plus a snapshot
runner extension exercising the new maker against the same Todo /
TodoCompleted naming the existing baselines use.

End-to-end verified locally: maker output matches baselines, dev
container compiles, listing make:bridge:* shows the new command.

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

framework/php/src/Maker/templates/EventSubscriber.tpl.php

@@ -0,0 +1,39 @@
+<?= "<?php\n" ?>
+
+declare(strict_types=1);
+
+namespace App\EventSubscriber;
+
+use App\Event\<?= $event_short ?>;
+use PhpQml\Bridge\PublisherInterface;
+use Symfony\Component\EventDispatcher\EventSubscriberInterface;
+
+/**
+ * Republishes <?= $event_short ?> on `app://event/<?= $event_topic ?>`.
+ * Auto-generated alongside the event class — wire `payload` to whatever
+ * shape you want QML clients to receive in the envelope's `data` field.
+ */
+final readonly class <?= $subscriber_short ?>
+
+ implements EventSubscriberInterface
+{
+    public function __construct(
+        private PublisherInterface $publisher,
+    ) {
+    }
+
+    public static function getSubscribedEvents(): array
+    {
+        return [
+            <?= $event_short ?>::class => '<?= $handler_method ?>',
+        ];
+    }
+
+    public function <?= $handler_method ?>(<?= $event_short ?> $event): void
+    {
+        $this->publisher->publish('app://event/<?= $event_topic ?>', [
+            'op'   => 'event',
+            'data' => $event->payload,
+        ]);
+    }
+}