Fix binary protobuf encoding for JSON serializer

- Use base64-encoded binary in JSON payload instead of {:binary, data} tuples
- V1.JSONSerializer cannot encode tuples, needs plain JSON objects
- Agent already sends/expects base64-encoded binary in 'binary' key

lib/towerops_web/channels/agent_channel.ex

@@ -65,19 +65,21 @@ defmodule ToweropsWeb.AgentChannel do
     job_list = %AgentJobList{jobs: jobs}
     binary = AgentJobList.encode(job_list)
 
-    push(socket, "jobs", {:binary, binary})
+    push(socket, "jobs", %{binary: Base.encode64(binary)})
     {:noreply, socket}
   end
 
   @impl true
-  def handle_in("result", {:binary, binary}, socket) do
+  def handle_in("result", %{"binary" => binary_b64}, socket) do
+    binary = Base.decode64!(binary_b64)
     result = SnmpResult.decode(binary)
     process_snmp_result(socket.assigns.organization_id, result)
     {:noreply, socket}
   end
 
   @impl true
-  def handle_in("heartbeat", {:binary, binary}, socket) do
+  def handle_in("heartbeat", %{"binary" => binary_b64}, socket) do
+    binary = Base.decode64!(binary_b64)
     heartbeat = AgentHeartbeat.decode(binary)
 
     metadata = %{
@@ -91,7 +93,8 @@ defmodule ToweropsWeb.AgentChannel do
   end
 
   @impl true
-  def handle_in("error", {:binary, binary}, socket) do
+  def handle_in("error", %{"binary" => binary_b64}, socket) do
+    binary = Base.decode64!(binary_b64)
     error = AgentError.decode(binary)
 
     Logger.error("Agent job error",