get_device_warnings() now returns only {code, meta} — severity, title,
message, and action are resolved centrally by netork's
WARNING_CATALOG (netork/core/device_warnings.py), not by the driver.
Keeps this driver independent of netork and avoids per-vendor drift in
how the same warning code is presented.
NetgearPlus: get_snmp_config() returns None (SNMP not accessible via HTTP API).
NetgearSmart: get_snmp_config() reads current community, fix_snmp configures
'snmp-server community public ro' via CLI.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>