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.types.ts

@@ -0,0 +1,38 @@
+export type EnrichedCallEvent = {
+    callSid: string;
+    eventType: 'ringing' | 'answered' | 'ended';
+    lead: {
+        id: string;
+        firstName: string;
+        lastName: string;
+        phone: string;
+        email?: string;
+        source?: string;
+        status?: string;
+        campaign?: string;
+        interestedService?: string;
+        age: number;
+        aiSummary?: string;
+        aiSuggestedAction?: string;
+        recentActivities: {
+            activityType: string;
+            summary: string;
+            occurredAt: string;
+            performedBy: string;
+        }[];
+    } | null;
+    callerPhone: string;
+    agentName: string;
+    timestamp: string;
+};
+
+export type DispositionPayload = {
+    callSid: string;
+    leadId: string | null;
+    disposition: string;
+    notes: string;
+    agentName: string;
+    callerPhone: string;
+    startedAt: string;
+    duration: number;
+};