feat: transcription fix + SLA write-back + real-time supervisor events

- Deepgram: multichannel=true + language=multi (captures both speakers, multilingual)
- LLM speaker identification (agent vs customer from conversational cues)
- Removed summarize=v2 (incompatible with multilingual)
- SLA computation on call creation (lead.createdAt → call.startedAt elapsed %)
- WebSocket: supervisor room + call:created broadcast for real-time updates
- Maint: clear-analysis-cache endpoint + scanKeys/deleteCache on SessionService
- AI chat: rules-engine context routing with dedicated system prompt

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

src/call-events/call-events.gateway.ts

@@ -35,6 +35,20 @@ export class CallEventsGateway {
         this.server.to(room).emit('call:incoming', event);
     }
 
+    // Broadcast to supervisors when a new call record is created
+    broadcastCallCreated(callData: any) {
+        this.logger.log('Broadcasting call:created to supervisor room');
+        this.server.to('supervisor').emit('call:created', callData);
+    }
+
+    // Supervisor registers to receive real-time updates
+    @SubscribeMessage('supervisor:register')
+    handleSupervisorRegister(@ConnectedSocket() client: Socket) {
+        client.join('supervisor');
+        this.logger.log(`Supervisor registered (socket: ${client.id})`);
+        client.emit('supervisor:registered', { room: 'supervisor' });
+    }
+
     // Agent registers when they open the Call Desk page
     @SubscribeMessage('agent:register')
     handleAgentRegister(