Endpoints:
- GET /api/supervisor/barge/sip-credentials — fetch SIP number from pool
- POST /api/supervisor/barge — initiate barge via Ozonetel apiId 63
- POST /api/supervisor/barge/mode — update mode (listen/whisper/barge)
- POST /api/supervisor/barge/end — cleanup session + Redis
SupervisorService extended with barge session tracking (in-memory Map).
Mode changes emit SSE events to agent: supervisor-whisper, supervisor-barge,
supervisor-left. Listen mode is silent (no event to agent).
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
