feat: add call events orchestrator with WebSocket gateway, wire Exotel → lookup → enrich → push flow

- CallEventsService orchestrates: Exotel webhook → lead lookup → AI enrichment → WebSocket push
- CallEventsGateway (Socket.IO /call-events namespace) with agent room registration and disposition handling
- EnrichedCallEvent/DispositionPayload types for frontend contract
- Disposition flow: creates Call record, updates lead status, logs lead activity
- Wired ExotelController to forward answered/ended events to CallEventsService
- forwardRef used to resolve circular dependency between gateway and service

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

src/call-events/call-events.module.ts

@@ -0,0 +1,12 @@
+import { Module } from '@nestjs/common';
+import { PlatformModule } from '../platform/platform.module';
+import { AiModule } from '../ai/ai.module';
+import { CallEventsService } from './call-events.service';
+import { CallEventsGateway } from './call-events.gateway';
+
+@Module({
+    imports: [PlatformModule, AiModule],
+    providers: [CallEventsService, CallEventsGateway],
+    exports: [CallEventsService, CallEventsGateway],
+})
+export class CallEventsModule {}