feat: multi-agent SIP with Redis session lockout

- SessionService: Redis-backed session lock/unlock/refresh with 1hr TTL
- AgentConfigService: queries Agent entity, caches per-member config
- Auth login: resolves agent config, locks Redis session, returns SIP credentials
- Auth logout: unlocks Redis session, Ozonetel logout, clears cache
- Auth heartbeat: refreshes Redis TTL every 5 minutes
- Added ioredis dependency

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

src/config/configuration.ts

@@ -12,6 +12,13 @@ export default () => ({
         subdomain: process.env.EXOTEL_SUBDOMAIN ?? 'api.exotel.com',
         webhookSecret: process.env.EXOTEL_WEBHOOK_SECRET ?? '',
     },
+    redis: {
+        url: process.env.REDIS_URL ?? 'redis://localhost:6379',
+    },
+    sip: {
+        domain: process.env.SIP_DOMAIN ?? 'blr-pub-rtc4.ozonetel.com',
+        wsPort: process.env.SIP_WS_PORT ?? '444',
+    },
     missedQueue: {
         pollIntervalMs: parseInt(process.env.MISSED_QUEUE_POLL_INTERVAL_MS ?? '30000', 10),
     },