Refactor handle_event SNMP test to reduce complexity

Extracted SNMP configuration extraction and connection testing
into separate helper functions, reducing cyclomatic complexity
from 11 to ~5.

- extract_snmp_config/1: Consolidates form data and params
- normalize_port/1: Handles port type conversion
- test_snmp_connection/1: Performs test and formats result

This makes the handle_event callback simpler and each concern
easier to test independently.

lib/towerops_web/live/equipment_live/form.ex

@@ -107,29 +107,8 @@ defmodule ToweropsWeb.EquipmentLive.Form do
 
   @impl true
   def handle_event("test_snmp", _params, socket) do
-    form_data = socket.assigns.form.data
-    params = socket.assigns.form.params
-
-    ip_address = params["ip_address"] || form_data.ip_address
-    snmp_community = params["snmp_community"] || form_data.snmp_community
-    snmp_version = params["snmp_version"] || form_data.snmp_version
-    snmp_port = params["snmp_port"] || form_data.snmp_port || 161
-
-    snmp_port =
-      case snmp_port do
-        port when is_integer(port) -> port
-        port when is_binary(port) -> String.to_integer(port)
-        _ -> 161
-      end
-
-    result =
-      case Snmp.test_connection(ip_address, snmp_community, snmp_version, snmp_port) do
-        {:ok, message} ->
-          %{success: true, message: message}
-
-        {:error, reason} ->
-          %{success: false, message: "Connection failed: #{inspect(reason)}"}
-      end
+    snmp_config = extract_snmp_config(socket.assigns.form)
+    result = test_snmp_connection(snmp_config)
 
     {:noreply, assign(socket, :snmp_test_result, result)}
   end
@@ -200,4 +179,35 @@ defmodule ToweropsWeb.EquipmentLive.Form do
         {:noreply, assign(socket, :form, to_form(changeset))}
     end
   end
+
+  defp extract_snmp_config(form) do
+    form_data = form.data
+    params = form.params
+
+    %{
+      ip_address: params["ip_address"] || form_data.ip_address,
+      snmp_community: params["snmp_community"] || form_data.snmp_community,
+      snmp_version: params["snmp_version"] || form_data.snmp_version,
+      snmp_port: normalize_port(params["snmp_port"] || form_data.snmp_port || 161)
+    }
+  end
+
+  defp normalize_port(port) when is_integer(port), do: port
+  defp normalize_port(port) when is_binary(port), do: String.to_integer(port)
+  defp normalize_port(_), do: 161
+
+  defp test_snmp_connection(config) do
+    case Snmp.test_connection(
+           config.ip_address,
+           config.snmp_community,
+           config.snmp_version,
+           config.snmp_port
+         ) do
+      {:ok, message} ->
+        %{success: true, message: message}
+
+      {:error, reason} ->
+        %{success: false, message: "Connection failed: #{inspect(reason)}"}
+    end
+  end
 end