Matrix Gateway:
- GET /internal/matrix/presence/{matrix_user_id} - get single user presence
- GET /internal/matrix/presence/bulk - get multiple users presence
City Service:
- GET /api/v1/agents/{agent_id}/presence - get agent presence via gateway
- get_matrix_presence_for_user() helper function
Task doc: TASK_PHASE_PRESENCE_LAYER_v1.md
