refactor: adopt Towerops.Result helpers in 8 call sites

Use Result.map, Result.unwrap_or, and Result.ok? where they replace
verbose case statements. Skipped sites where return shapes (3-tuples,
:skipped atoms) prevent clean adoption.

- proto/wire.ex: skip_field varint and length-delimited use Result.map
- organizations.ex: list_organization_ids uses Result.unwrap_or([])
- security/four_oh_four_tracker.ex: count_404s uses Result.unwrap_or(0)
- billing/billing_notifier.ex: at-least-one-success check uses Result.ok?
- topology.ex: two success-counting sites use Result.ok?
- snmp/wireless_client_discovery.ex: walk_or_empty uses Result.unwrap_or(%{})

lib/towerops/billing/billing_notifier.ex

@@ -12,6 +12,7 @@ defmodule Towerops.Billing.BillingNotifier do
 
   alias Towerops.Mailer
   alias Towerops.Organizations
+  alias Towerops.Result
 
   require Logger
 
@@ -84,7 +85,7 @@ defmodule Towerops.Billing.BillingNotifier do
         end)
 
       # Return success if at least one email was sent
-      if Enum.any?(results, &match?({:ok, _}, &1)) do
+      if Enum.any?(results, &Result.ok?/1) do
         {:ok, results}
       else
         {:error, :all_emails_failed}

lib/towerops/organizations.ex

@@ -18,6 +18,7 @@ defmodule Towerops.Organizations do
   alias Towerops.Organizations.Policy
   alias Towerops.Organizations.SubscriptionLimits
   alias Towerops.Repo
+  alias Towerops.Result
   alias Towerops.Sites.Site
 
   ## Organizations
@@ -35,10 +36,7 @@ defmodule Towerops.Organizations do
       |> Enum.to_list()
     end
     |> Repo.transaction()
-    |> case do
-      {:ok, ids} -> ids
-      {:error, _} -> []
-    end
+    |> Result.unwrap_or([])
   end
 
   @doc """

lib/towerops/proto/wire.ex

@@ -8,6 +8,8 @@ defmodule Towerops.Proto.Wire do
 
   import Bitwise
 
+  alias Towerops.Result
+
   # Wire type constants
   @wire_varint 0
   @wire_64bit 1
@@ -179,10 +181,7 @@ defmodule Towerops.Proto.Wire do
   """
   @spec skip_field(0..5, binary()) :: {:ok, binary()} | {:error, wire_error()}
   def skip_field(@wire_varint, data) do
-    case decode_varint(data) do
-      {:ok, {_value, rest}} -> {:ok, rest}
-      {:error, e} -> {:error, e}
-    end
+    Result.map(decode_varint(data), fn {_value, rest} -> rest end)
   end
 
   def skip_field(@wire_64bit, data) when byte_size(data) >= 8 do
@@ -193,10 +192,7 @@ defmodule Towerops.Proto.Wire do
   def skip_field(@wire_64bit, _data), do: {:error, :unexpected_eof}
 
   def skip_field(@wire_length_delimited, data) do
-    case decode_bytes(data) do
-      {:ok, {_field_data, rest}} -> {:ok, rest}
-      {:error, e} -> {:error, e}
-    end
+    Result.map(decode_bytes(data), fn {_field_data, rest} -> rest end)
   end
 
   def skip_field(@wire_32bit, data) when byte_size(data) >= 4 do

lib/towerops/security/four_oh_four_tracker.ex

@@ -6,6 +6,7 @@ defmodule Towerops.Security.FourOhFourTracker do
   When an IP hits 5+ unique 404s, a ban is created/escalated.
   """
 
+  alias Towerops.Result
   alias Towerops.Security.BruteForce
 
   require Logger
@@ -59,10 +60,7 @@ defmodule Towerops.Security.FourOhFourTracker do
     conn = Towerops.Redix
 
     try do
-      case Redix.command(conn, ["SCARD", key]) do
-        {:ok, count} -> count
-        {:error, _} -> 0
-      end
+      Result.unwrap_or(Redix.command(conn, ["SCARD", key]), 0)
     catch
       :exit, _ -> 0
     end

lib/towerops/snmp/wireless_client_discovery.ex

@@ -8,6 +8,7 @@ defmodule Towerops.Snmp.WirelessClientDiscovery do
   - MikroTik RouterOS: mtxrWlRtabTable
   """
 
+  alias Towerops.Result
   alias Towerops.Snmp.Client
   alias Towerops.Snmp.WirelessClientDiscovery.Parser
 
@@ -186,10 +187,7 @@ defmodule Towerops.Snmp.WirelessClientDiscovery do
   # --- Helpers ---
 
   defp walk_or_empty(client_opts, oid) do
-    case Client.walk(client_opts, oid) do
-      {:ok, entries} -> {:ok, entries}
-      {:error, _} -> {:ok, %{}}
-    end
+    {:ok, Result.unwrap_or(Client.walk(client_opts, oid), %{})}
   end
 
   # Group walk results by row index, extracting the index suffix from OID keys

lib/towerops/topology.ex

@@ -10,6 +10,7 @@ defmodule Towerops.Topology do
   alias Towerops.Devices
   alias Towerops.Devices.Device
   alias Towerops.Repo
+  alias Towerops.Result
   alias Towerops.Snmp.ArpEntry
   alias Towerops.Snmp.Device, as: SnmpDevice
   alias Towerops.Snmp.Interface
@@ -388,7 +389,7 @@ defmodule Towerops.Topology do
         |> Enum.map(&upsert_grouped_evidence(&1, device.id, lookup, now))
         |> Enum.reject(&(&1 == :skip))
 
-      has_changes = Enum.any?(results, &match?({:ok, _}, &1))
+      has_changes = Enum.any?(results, &Result.ok?/1)
 
       # Auto-inference disabled - device type is now manual-only
       # maybe_update_device_role(device)
@@ -1111,7 +1112,7 @@ defmodule Towerops.Topology do
       {:ok, %{neighbors: neighbors}} ->
         now = DateTime.utc_now()
         results = Enum.map(neighbors, &upsert_device_neighbor(device_id, &1, now))
-        success_count = Enum.count(results, &match?({:ok, _}, &1))
+        success_count = Enum.count(results, &Result.ok?/1)
         {:ok, success_count}
 
       {:error, reason} = error ->