Improve weekly hours form (#5528)

templates/quick-entry/index.html.twig

@@ -13,11 +13,15 @@
             {{ form_errors(form) }}
         {% endblock %}
         {% block box_after %}
+            {% if locked %}
+                {{ widgets.alert('warning', 'The chosen date is already locked.'|trans({}, 'validators')) }}
+            {% else %}
             <input type="submit" value="{{ 'action.save'|trans }}" class="btn btn-primary" />
             <button type="button" class="btn btn-success add-item-link" data-collection-prototype="{{ form.rows.vars.id }}" data-collection-holder="ts-collection">
                 {{ icon('create', true) }}
                 {{ 'action.add'|trans }}
             </button>
+            {% endif %}
             {{ form_end(form) }}
         {% endblock %}
         {# "table-responsive" does not work, because that would render dropdowns at the bottom behind the container #}