refactor: replace more cond expressions with guarded clauses

- CoordinateUtils.normalize_longitude / normalize_latitude: recursion
  and clamping move into the function head via numeric guards.
- Shared.PacketUtils.map_label: dispatch on data_type + fallback via
  multi-clause helpers (map_label_for/2, prefer_name/2) instead of a
  three-branch cond with inner `if`s.
- MapLive.DataBuilder.get_received_at: pattern-match the atom- and
  string-key packet shapes in the function head.

No behavior change; all 1567 tests and 27 property checks still pass,
dialyzer remains clean.

lib/aprsme_web/live/map_live/data_builder.ex

@@ -601,13 +601,9 @@ defmodule AprsmeWeb.MapLive.DataBuilder do
   end
 
   @spec get_received_at(map()) :: DateTime.t() | nil
-  defp get_received_at(packet) do
-    cond do
-      Map.has_key?(packet, :received_at) -> packet.received_at
-      Map.has_key?(packet, "received_at") -> packet["received_at"]
-      true -> nil
-    end
-  end
+  defp get_received_at(%{received_at: value}), do: value
+  defp get_received_at(%{"received_at" => value}), do: value
+  defp get_received_at(_packet), do: nil
 
   # Helper to get locale from socket
   @spec get_locale(Socket.t()) :: String.t()

lib/aprsme_web/live/shared/coordinate_utils.ex

@@ -90,15 +90,8 @@ defmodule AprsmeWeb.Live.Shared.CoordinateUtils do
   Normalize longitude to the -180 to 180 range.
   """
   @spec normalize_longitude(number()) :: number()
-  def normalize_longitude(lon) when is_number(lon) do
-    # Wrap longitude to -180 to 180 range
-    cond do
-      lon > 180 -> normalize_longitude(lon - 360)
-      lon < -180 -> normalize_longitude(lon + 360)
-      true -> lon
-    end
-  end
-
+  def normalize_longitude(lon) when is_number(lon) and lon > 180, do: normalize_longitude(lon - 360)
+  def normalize_longitude(lon) when is_number(lon) and lon < -180, do: normalize_longitude(lon + 360)
   def normalize_longitude(lon), do: lon
 
   @doc """
@@ -106,14 +99,8 @@ defmodule AprsmeWeb.Live.Shared.CoordinateUtils do
   Latitude cannot wrap, so we clamp to valid range.
   """
   @spec normalize_latitude(number()) :: number()
-  def normalize_latitude(lat) when is_number(lat) do
-    cond do
-      lat > 90 -> 90.0
-      lat < -90 -> -90.0
-      true -> lat
-    end
-  end
-
+  def normalize_latitude(lat) when is_number(lat) and lat > 90, do: 90.0
+  def normalize_latitude(lat) when is_number(lat) and lat < -90, do: -90.0
   def normalize_latitude(lat), do: lat
 
   @doc """

lib/aprsme_web/live/shared/packet_utils.ex

@@ -246,22 +246,23 @@ defmodule AprsmeWeb.Live.Shared.PacketUtils do
   """
   @spec map_label(map()) :: String.t()
   def map_label(packet) do
-    data_type = get_packet_field(packet, :data_type, "")
-
-    cond do
-      data_type == "object" ->
-        object_name = get_packet_field(packet, :object_name, "")
-        if object_name == "", do: get_packet_field(packet, :sender, ""), else: object_name
-
-      data_type == "item" ->
-        item_name = get_packet_field(packet, :item_name, "")
-        if item_name == "", do: get_packet_field(packet, :sender, ""), else: item_name
-
-      true ->
-        get_packet_field(packet, :sender, "")
-    end
+    map_label_for(get_packet_field(packet, :data_type, ""), packet)
   end
 
+  defp map_label_for("object", packet) do
+    prefer_name(get_packet_field(packet, :object_name, ""), packet)
+  end
+
+  defp map_label_for("item", packet) do
+    prefer_name(get_packet_field(packet, :item_name, ""), packet)
+  end
+
+  defp map_label_for(_data_type, packet), do: get_packet_field(packet, :sender, "")
+
+  # Use `name` when non-empty, otherwise fall back to the packet sender.
+  defp prefer_name("", packet), do: get_packet_field(packet, :sender, "")
+  defp prefer_name(name, _packet), do: name
+
   defp non_empty_string?(value) when is_binary(value), do: String.trim(value) != ""
   defp non_empty_string?(_), do: false