refactor(email): share build/deliver skeleton across join emails

lib/mv_web/emails/join_already_member_email.ex

@@ -5,15 +5,9 @@ defmodule MvWeb.Emails.JoinAlreadyMemberEmail do
   Used for anti-enumeration: the UI shows the same success message; only the email
   informs the recipient. Uses the unified email layout.
   """
-  use Phoenix.Swoosh,
-    view: MvWeb.EmailsView,
-    layout: {MvWeb.EmailLayoutView, "layout.html"}
-
-  use MvWeb, :verified_routes
-  import Swoosh.Email
   use Gettext, backend: MvWeb.Gettext, otp_app: :mv
 
-  alias Mv.Mailer
+  alias MvWeb.Emails.JoinEmail
 
   @doc """
   Sends the "already a member" notice to the given address.
@@ -23,20 +17,6 @@ defmodule MvWeb.Emails.JoinAlreadyMemberEmail do
   def send(email_address) when is_binary(email_address) do
     subject = gettext("Membership application – already a member")
 
-    assigns = %{
-      subject: subject,
-      app_name: Mailer.mail_from() |> elem(0),
-      locale: Gettext.get_locale(MvWeb.Gettext)
-    }
-
-    email =
-      new()
-      |> from(Mailer.mail_from())
-      |> to(email_address)
-      |> subject(subject)
-      |> put_view(MvWeb.EmailsView)
-      |> render_body("join_already_member.html", assigns)
-
-    Mailer.deliver(email, Mailer.smtp_config())
+    JoinEmail.deliver(email_address, "join_already_member.html", subject)
   end
 end