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/platform/platform.types.ts

@@ -49,6 +49,7 @@ export type CreateCallInput = {
     disposition?: string;
     callNotes?: string;
     leadId?: string;
+    sla?: number;
 };
 
 export type CreateLeadActivityInput = {