Addresses UGREEN issue #28: the advertised UGOS API and SNMP methods previously performed only a web reachability check.
- Add UGOS API authentication with RSA-encrypted login, reusable sessions, bounded reauthentication, WebSocket telemetry keepalive, and encrypted disk transport when supported by the firmware.
- Collect system, CPU, RAM, temperature, uptime, pool, volume and disk information from supported UGOS responses; distinguish unavailable metrics and hardware warnings.
- Add SNMP v2/v3 standard-MIB collection and mode-specific connection settings. Preserve masked credentials, legacy host-only configurations and multiple SNMP services on different ports.
- Make web-check mode explicitly report reachability only and update configuration examples and documentation.
Validation: complete smoke suite, API/HTTP/WebSocket fixtures, real loopback UDP SNMP v2/v3 SHA-AES fixtures, settings/secret-preservation regressions, JavaScript and inline-script syntax checks, production dependency audit (0 vulnerabilities), and local application health/readiness/API checks.
Physical UGREEN hardware validation is still pending. UGOS APIs are unofficial and firmware-dependent; model and firmware feedback from issue #28 is requested before considering that issue resolved.