feat: add Exotel webhook controller and service for call event parsing

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/exotel/exotel.types.ts

@@ -0,0 +1,35 @@
+// Exotel webhook payload (from their API docs)
+export type ExotelWebhookPayload = {
+    event_details: {
+        event_type: 'answered' | 'terminal';
+    };
+    call_details: {
+        call_sid: string;
+        direction: 'inbound' | 'outbound';
+        call_status?: string;
+        total_talk_time?: number;
+        assigned_agent_details?: {
+            name: string;
+            number: string;
+        };
+        customer_details?: {
+            number: string;
+            name?: string;
+        };
+        recordings?: { url: string }[];
+    };
+};
+
+// Internal call event (normalized)
+export type CallEvent = {
+    exotelCallSid: string;
+    eventType: 'ringing' | 'answered' | 'ended';
+    direction: 'inbound' | 'outbound';
+    callerPhone: string;
+    agentName: string;
+    agentPhone: string;
+    duration?: number;
+    recordingUrl?: string;
+    callStatus?: string;
+    timestamp: string;
+};