Changes:
- Updated backend/src/services/mqtt.js to use LEGACY_API_USERNAME and LEGACY_API_PASSWORD from .env
- Updated services/api.ts with new robster credentials
- Added Legacy API and MQTT credentials to backend/.env.example
- MQTT service now falls back to LEGACY_API_* env vars if MQTT_* not set
This ensures all services use consistent, up-to-date credentials from environment configuration.
Sergei
869f5d1305