Replace abandoned earmark with mdex for markdown rendering

lib/bds/desktop/shell_live/chat_editor.ex

@@ -546,9 +546,9 @@ defmodule BDS.Desktop.ShellLive.ChatEditor do
   @spec markdown_html(binary()) :: Phoenix.HTML.Safe.t()
   def markdown_html(content) when is_binary(content) do
     html =
-      case Earmark.as_html(content, escape: true) do
-        {:ok, rendered, _messages} -> rendered
-        {:error, rendered, _messages} -> rendered
+      case MDEx.to_html(content) do
+        {:ok, rendered} -> rendered
+        {:error, _reason} -> ""
       end
       |> rewrite_external_images()