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/config/services.yaml

@@ -41,3 +41,7 @@ when@dev:
         PhpQml\Bridge\Maker\BridgeWindowMaker:
             arguments:
                 $qmlPath: '%bridge.qml_path%'
+
+        PhpQml\Bridge\Maker\BridgeEventMaker:
+            arguments:
+                $qmlPath: '%bridge.qml_path%'