debug: add SNMPv3 parameter logging

Added info-level logging to show what parameters are being passed to
SnmpKit for SNMPv3 requests. This will help diagnose encoding errors.

lib/towerops/snmp/client.ex

@@ -66,6 +66,11 @@ defmodule Towerops.Snmp.Client do
     target = build_target(opts)
     snmp_opts = build_snmp_opts(opts)
 
+    # Debug logging for SNMPv3
+    if Keyword.get(snmp_opts, :version) == :v3 do
+      Logger.info("SNMPv3 request to #{target}: #{inspect(snmp_opts, pretty: true)}")
+    end
+
     # Resolve MIB name to numeric OID if needed
     resolved_oid = resolve_mib_name(oid)