Reduce memory usage in IEx autocomplete module listing

Use :erlang.loaded/0 instead of :code.all_loaded/0 since we only need
module names, not file paths. The latter copies the full path for every
loaded module, which on production systems with many dependencies
caused significant memory spikes (measured 2.8MB -> 172KB on a real pod).

Also replace Enum.sort/1 |> Enum.dedup/1 with :lists.usort/1 to
eliminate one intermediate list allocation.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: dkuku

lib/iex/lib/iex/autocomplete.ex

@@ -604,8 +604,7 @@ defmodule IEx.Autocomplete do
 
   defp match_modules(hint, elixir_root?) do
     get_modules(elixir_root?)
-    |> Enum.sort()
-    |> Enum.dedup()
+    |> :lists.usort()
     |> Enum.drop_while(&(not String.starts_with?(&1, hint)))
     |> Enum.take_while(&String.starts_with?(&1, hint))
   end
@@ -615,7 +614,7 @@ defmodule IEx.Autocomplete do
   end
 
   defp get_modules(false) do
-    modules = Enum.map(:code.all_loaded(), &Atom.to_string(elem(&1, 0)))
+    modules = Enum.map(:erlang.loaded(), &Atom.to_string/1)
 
     case :code.get_mode() do
       :interactive -> modules ++ get_modules_from_applications()