Persist timezones in the server

Add a beacon to persist timezones when these change (or the first time)

test/controllers/my/timezones_controller_test.rb

@@ -0,0 +1,15 @@
+require "test_helper"
+
+class My::TimezonesControllerTest < ActionDispatch::IntegrationTest
+  setup do
+    sign_in_as :kevin
+  end
+
+  test "update" do
+    time_zone = ActiveSupport::TimeZone["America/New_York"]
+
+    assert_not_equal time_zone, users(:kevin).timezone
+    patch my_timezone_path, params: { timezone_name: "America/New_York" }
+    assert_equal time_zone, users(:kevin).reload.timezone
+  end
+end