feat: add join request resource

lib/membership/join_request/changes/confirm_request.ex

@@ -0,0 +1,17 @@
+defmodule Mv.Membership.JoinRequest.Changes.ConfirmRequest do
+  @moduledoc """
+  Sets the join request to submitted (confirmation link clicked).
+
+  Used by the confirm action after the user clicks the confirmation link.
+  Token hash is kept so that a second click (idempotent) can still find the record
+  and return success without changing it.
+  """
+  use Ash.Resource.Change
+
+  @spec change(Ash.Changeset.t(), keyword(), Ash.Resource.Change.context()) :: Ash.Changeset.t()
+  def change(changeset, _opts, _context) do
+    changeset
+    |> Ash.Changeset.force_change_attribute(:status, :submitted)
+    |> Ash.Changeset.force_change_attribute(:submitted_at, DateTime.utc_now())
+  end
+end