Fix remaining nesting depth issues

Extracts nested logic into helper functions to comply with Credo
requirements (max nesting depth 2):

- data_builder.ex: Extract historical packet data building
  (build_historical_packet_data/2)
  Reduces depth 3 -> depth 2

- streaming_packets_pubsub.ex: Extract subscriber filtering and messaging
  (send_to_matching_subscribers/5)
  Removes conditional check by sending cleanup message unconditionally
  (GenServer handles empty list gracefully)
  Reduces depth 3 -> depth 2

- historical_loader.ex: Extract RF path station loading logic
  (maybe_load_rf_path_stations/3)
  Reduces depth 3 -> depth 2

- packet_processor.ex: Extract marker popup logic
  (send_marker_with_popup_check/2)
  Reduces depth 3 -> depth 2

Fixes all 4 remaining Credo nesting depth issues.
All nesting depth issues now resolved (0 remaining).

lib/aprsme/streaming_packets_pubsub.ex

@@ -119,17 +119,7 @@ defmodule Aprsme.StreamingPacketsPubSub do
       server_pid = self()
 
       Aprsme.BroadcastTaskSupervisor.async_execute(fn ->
-        dead_pids =
-          subscribers
-          |> Stream.filter(fn {_pid, bounds} -> packet_in_bounds?(lat, lon, bounds) end)
-          |> Enum.reduce([], fn {pid, _bounds}, acc ->
-            send_to_subscriber_if_alive(pid, packet, acc)
-          end)
-
-        # Send dead pids back to GenServer for cleanup
-        if dead_pids != [] do
-          send(server_pid, {:cleanup_dead_subscribers, dead_pids})
-        end
+        send_to_matching_subscribers(subscribers, lat, lon, packet, server_pid)
       end)
     end
 
@@ -182,6 +172,18 @@ defmodule Aprsme.StreamingPacketsPubSub do
     lat_in_bounds and lon_in_bounds
   end
 
+  defp send_to_matching_subscribers(subscribers, lat, lon, packet, server_pid) do
+    dead_pids =
+      subscribers
+      |> Stream.filter(fn {_pid, bounds} -> packet_in_bounds?(lat, lon, bounds) end)
+      |> Enum.reduce([], fn {pid, _bounds}, acc ->
+        send_to_subscriber_if_alive(pid, packet, acc)
+      end)
+
+    # Send dead pids back to GenServer for cleanup
+    send(server_pid, {:cleanup_dead_subscribers, dead_pids})
+  end
+
   defp send_to_subscriber_if_alive(pid, packet, acc) do
     if Process.alive?(pid) do
       send(pid, {:streaming_packet, packet})

lib/aprsme_web/live/map_live/data_builder.ex

@@ -184,10 +184,7 @@ defmodule AprsmeWeb.MapLive.DataBuilder do
             filter_historical_by_distance(historical, most_recent_lat, most_recent_lon)
 
           # Build data for remaining historical packets
-          historical_data =
-            filtered_historical
-            |> Enum.map(fn packet -> build_minimal_packet_data(packet, false, has_weather) end)
-            |> Enum.filter(& &1)
+          historical_data = build_historical_packet_data(filtered_historical, has_weather)
 
           # Combine most recent and filtered historical
           Enum.filter([most_recent_data | historical_data], & &1)
@@ -628,4 +625,10 @@ defmodule AprsmeWeb.MapLive.DataBuilder do
       false
     end
   end
+
+  defp build_historical_packet_data(filtered_historical, has_weather) do
+    filtered_historical
+    |> Enum.map(fn packet -> build_minimal_packet_data(packet, false, has_weather) end)
+    |> Enum.filter(& &1)
+  end
 end

lib/aprsme_web/live/map_live/historical_loader.ex

@@ -197,12 +197,7 @@ defmodule AprsmeWeb.MapLive.HistoricalLoader do
           end
 
         # If tracking a callsign and this is the first batch, also load RF path stations
-        socket =
-          if socket.assigns.tracked_callsign != "" and batch_offset == 0 do
-            load_rf_path_stations(socket, historical_packets)
-          else
-            socket
-          end
+        socket = maybe_load_rf_path_stations(socket, batch_offset, historical_packets)
 
         process_loaded_packets(socket, historical_packets, packet_data_list, batch_offset)
       else
@@ -424,6 +419,14 @@ defmodule AprsmeWeb.MapLive.HistoricalLoader do
     socket
   end
 
+  defp maybe_load_rf_path_stations(socket, batch_offset, historical_packets) do
+    if socket.assigns.tracked_callsign != "" and batch_offset == 0 do
+      load_rf_path_stations(socket, historical_packets)
+    else
+      socket
+    end
+  end
+
   defp load_rf_path_stations(socket, packets) do
     # Extract unique RF path stations from all packets
     rf_path_stations =

lib/aprsme_web/live/map_live/packet_processor.ex

@@ -109,13 +109,7 @@ defmodule AprsmeWeb.MapLive.PacketProcessor do
       marker_data = PacketUtils.build_packet_data(packet, true, get_locale(socket))
 
       if marker_data do
-        # Only show new packet popup if no station popup is currently open
-        if socket.assigns.station_popup_open do
-          # Send without opening popup to avoid interrupting user
-          LiveView.push_event(socket, "new_packet", Map.put(marker_data, :openPopup, false))
-        else
-          LiveView.push_event(socket, "new_packet", marker_data)
-        end
+        send_marker_with_popup_check(socket, marker_data)
       else
         socket
       end
@@ -167,4 +161,13 @@ defmodule AprsmeWeb.MapLive.PacketProcessor do
     # This function should be moved to DisplayManager module
     socket
   end
+
+  defp send_marker_with_popup_check(socket, marker_data) do
+    if socket.assigns.station_popup_open do
+      # Send without opening popup to avoid interrupting user
+      LiveView.push_event(socket, "new_packet", Map.put(marker_data, :openPopup, false))
+    else
+      LiveView.push_event(socket, "new_packet", marker_data)
+    end
+  end
 end