feat: call control, recording, CDR, missed calls, live call assist

- Call Control API (CONFERENCE/HOLD/MUTE/KICK_CALL)
- Recording pause/unpause
- Fetch CDR Detailed (call history with recordings)
- Abandon Calls (missed calls from Ozonetel)
- Call Assist WebSocket gateway (Deepgram STT + OpenAI suggestions)
- Call Assist service (lead context loading)

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

src/call-assist/call-assist.module.ts

@@ -0,0 +1,10 @@
+import { Module } from '@nestjs/common';
+import { CallAssistGateway } from './call-assist.gateway';
+import { CallAssistService } from './call-assist.service';
+import { PlatformModule } from '../platform/platform.module';
+
+@Module({
+    imports: [PlatformModule],
+    providers: [CallAssistGateway, CallAssistService],
+})
+export class CallAssistModule {}