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/auth/session.service.ts

@@ -59,4 +59,19 @@ export class SessionService implements OnModuleInit {
     async setCache(key: string, value: string, ttlSeconds: number): Promise<void> {
         await this.redis.set(key, value, 'EX', ttlSeconds);
     }
+
+    async deleteCache(key: string): Promise<void> {
+        await this.redis.del(key);
+    }
+
+    async scanKeys(pattern: string): Promise<string[]> {
+        const keys: string[] = [];
+        let cursor = '0';
+        do {
+            const [next, batch] = await this.redis.scan(cursor, 'MATCH', pattern, 'COUNT', 100);
+            cursor = next;
+            keys.push(...batch);
+        } while (cursor !== '0');
+        return keys;
+    }
 }