The previous attempt added a rule without src= which lands in the global
nftables input chain. Traffic from the management interface (br-ap.10)
jumps immediately to input_mgmt, so the global rule was never reached.
Now detects the management zone name by finding the zone whose allow-SSH
rule already exists (the named rule pattern allow_ssh_from_<zone>).
Removes any mis-scoped previous SNMP rule, then adds a named UCI rule
allow_snmp_from_<zone> with src=<zone> so fw4 places it in the correct
chain (input_mgmt). Persists across reboots via uci commit + fw4 reload.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
