add diagnostic logging for agent result handling

lib/towerops_web/channels/agent_channel.ex

@@ -334,6 +334,8 @@ defmodule ToweropsWeb.AgentChannel do
   @impl true
   @spec handle_in(String.t(), map(), socket()) :: {:noreply, socket()}
   def handle_in("result", %{"binary" => binary_b64}, socket) when is_binary(binary_b64) do
+    Logger.info("Received SNMP result from agent (binary size: #{byte_size(binary_b64)})")
+
     with {:ok, binary} <- safe_base64_decode(binary_b64),
          {:ok, result} <- Validator.validate_snmp_result(binary) do
       maybe_debug_log(socket, "Received SNMP result from agent",
@@ -547,6 +549,17 @@ defmodule ToweropsWeb.AgentChannel do
     end
   end
 
+  # Catch-all for unmatched events (diagnostic)
+  def handle_in(event, payload, socket) do
+    Logger.warning("Unhandled agent channel event",
+      event: event,
+      payload_keys: Map.keys(payload),
+      agent_token_id: socket.assigns.agent_token_id
+    )
+
+    {:noreply, socket}
+  end
+
   # Private helpers
 
   @spec handle_validated_mikrotik_result(MikrotikResult.t(), socket()) :: {:noreply, socket()}