feat: build infrastructure

Co-authored-by: Copilot <copilot@github.com>

lib/mix/tasks/bds.package.ex

@@ -0,0 +1,49 @@
+defmodule Mix.Tasks.Bds.Package do
+  @moduledoc false
+
+  use Mix.Task
+
+  @shortdoc "Packages built releases into a redistributable platform payload"
+
+  @impl Mix.Task
+  def run(args) do
+    {opts, positional, _invalid} =
+      OptionParser.parse(args,
+        strict: [output: :string, version: :string, app_release: :string, mcp_release: :string]
+      )
+
+    platform = positional |> List.first() |> normalize_platform_arg()
+    version = opts[:version] || Mix.Project.config()[:version]
+    env_name = Atom.to_string(Mix.env())
+
+    package_opts = [
+      platform: platform,
+      version: version,
+      output_dir: opts[:output] || Path.expand("dist/#{platform}", File.cwd!()),
+      app_release_source: opts[:app_release] || Path.expand("_build/#{env_name}/rel/bds", File.cwd!()),
+      mcp_release_source: opts[:mcp_release] || Path.expand("_build/#{env_name}/rel/bds_mcp", File.cwd!())
+    ]
+
+    case BDS.ReleasePackaging.package(package_opts) do
+      {:ok, metadata} ->
+        Mix.shell().info("Packaged #{metadata.payload_name} at #{metadata.archive_path}")
+
+      {:error, reason} ->
+        Mix.raise("Packaging failed: #{inspect(reason)}")
+    end
+  end
+
+  defp normalize_platform_arg(nil), do: current_platform()
+  defp normalize_platform_arg("macos"), do: :macos
+  defp normalize_platform_arg("linux"), do: :linux
+  defp normalize_platform_arg("windows"), do: :windows
+  defp normalize_platform_arg(other), do: Mix.raise("Unsupported platform #{inspect(other)}")
+
+  defp current_platform do
+    case :os.type() do
+      {:win32, _type} -> :windows
+      {:unix, :darwin} -> :macos
+      {:unix, _type} -> :linux
+    end
+  end
+end