feat: event bus with Redpanda + AI insight consumer

- EventBusService: Kafka/Redpanda pub/sub with kafkajs, graceful fallback when broker unavailable
- Topics: call.completed, call.missed, agent.state
- AiInsightConsumer: on call.completed, fetches lead activity → OpenAI generates summary + suggested action → updates Lead entity on platform
- Disposition endpoint emits call.completed event after Ozonetel dispose
- EventsModule registered as @Global for cross-module injection
- Redpanda container added to VPS docker-compose
- Docker image rebuilt for linux/amd64 with kafkajs dependency

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

package.json

@@ -35,6 +35,7 @@
     "ai": "^6.0.116",
     "axios": "^1.13.6",
     "ioredis": "^5.10.1",
+    "kafkajs": "^2.2.4",
     "reflect-metadata": "^0.2.2",
     "rxjs": "^7.8.1",
     "socket.io": "^4.8.3",