partition by org_id and add auth

lib/customer_service_web/plugs/extract_organization_id.ex

@@ -0,0 +1,22 @@
+defmodule CustomerServiceWeb.Plugs.ExtractOrganizationId do
+  @moduledoc """
+  Extract `X-Organization-Id` request header.
+
+  Stores the organization identifier in conn.private[__MODULE__] for downstream authorization checks.
+  """
+
+  @behaviour Plug
+
+  import Plug.Conn, only: [get_req_header: 2, put_private: 3]
+
+  @impl Plug
+  def init(_opts), do: %{}
+
+  @impl Plug
+  def call(conn, _opts) do
+    case get_req_header(conn, "x-organization-id") do
+      [org_id | _rest] -> put_private(conn, __MODULE__, org_id)
+      [] -> put_private(conn, __MODULE__, nil)
+    end
+  end
+end