fix(gateway/bluebubbles): remove invalid "message" from webhook event registration

The BlueBubbles adapter registers its webhook with three events:
["new-message", "updated-message", "message"]. The third, "message",
is not a valid event type in the BlueBubbles server API — BB rejects
the registration payload with HTTP 400 Bad Request.

Currently this is masked by the "crash resilience" check in
_register_webhook, which reuses any existing registration matching the
webhook URL and short-circuits before reaching the API call. So an
already-registered webhook from a prior run keeps working. But any fresh
install, or any restart after _unregister_webhook has run during a clean
shutdown, fails to re-register and silently stops receiving messages.

Observed in production: after a gateway restart in v0.9.0 (which auto-
unregisters on shutdown), the next startup hit this 400 and the bot went
silent until the invalid event was removed.

BlueBubbles documents "new-message" and "updated-message" as the message
event types (see https://docs.bluebubbles.app/). There is no "message"
event, and no harm in dropping it — the two remaining events cover all
inbound message webhooks.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

gateway/platforms/bluebubbles.py

@@ -257,7 +257,7 @@ class BlueBubblesAdapter(BasePlatformAdapter):
 
         payload = {
             "url": webhook_url,
-            "events": ["new-message", "updated-message", "message"],
+            "events": ["new-message", "updated-message"],
         }
 
         try: