fix(member): order member list chronologically by custom :date fields

test/mv_web/member_live/index_custom_fields_sorting_test.exs

@@ -231,6 +231,63 @@ defmodule MvWeb.MemberLive.IndexCustomFieldsSortingTest do
     assert has_element?(view, "[data-testid='custom_field_#{field.id}'][aria-label='ascending']")
   end
 
+  test "sorts members chronologically by a :date custom field (ascending)", %{conn: conn} do
+    system_actor = Mv.Helpers.SystemActor.get_system_actor()
+
+    # Dates chosen to expose the day-first term-ordering trap: term order of the
+    # %Date{} structs compares day, then month, then year, which would place
+    # 02.07.1986 (day 02) before 29.01.1981 (day 29). Chronologically 1981 < 1982 < 1986.
+    members_and_dates = [
+      {"EightySix", ~D[1986-07-02]},
+      {"EightyOne", ~D[1981-01-29]},
+      {"EightyTwo", ~D[1982-03-01]}
+    ]
+
+    {:ok, field} =
+      CustomField
+      |> Ash.Changeset.for_create(:create, %{
+        name: "birth_date",
+        value_type: :date,
+        show_in_overview: true
+      })
+      |> Ash.create(actor: system_actor)
+
+    for {first_name, date} <- members_and_dates do
+      {:ok, member} =
+        Mv.Membership.create_member(
+          %{
+            first_name: first_name,
+            last_name: "Test",
+            email: "#{String.downcase(first_name)}@example.com"
+          },
+          actor: system_actor
+        )
+
+      {:ok, _cfv} =
+        CustomFieldValue
+        |> Ash.Changeset.for_create(:create, %{
+          member_id: member.id,
+          custom_field_id: field.id,
+          value: %{"_union_type" => "date", "_union_value" => Date.to_iso8601(date)}
+        })
+        |> Ash.create(actor: system_actor)
+    end
+
+    conn = conn_with_oidc_user(conn)
+
+    {:ok, view, _html} =
+      live(conn, "/members?query=&sort_field=custom_field_#{field.id}&sort_order=asc")
+
+    html = render(view)
+
+    {one_idx, _} = :binary.match(html, "EightyOne")
+    {two_idx, _} = :binary.match(html, "EightyTwo")
+    {six_idx, _} = :binary.match(html, "EightySix")
+
+    assert one_idx < two_idx, "29.01.1981 must come before 01.03.1982 in ascending order"
+    assert two_idx < six_idx, "01.03.1982 must come before 02.07.1986 in ascending order"
+  end
+
   test "NULL values and empty strings are always sorted last (ASC)", %{conn: conn} do
     system_actor = Mv.Helpers.SystemActor.get_system_actor()