feat(course_page.html): show notice if course doesn't have an assigned product

home/templates/home/course_page.html

@@ -49,6 +49,10 @@
       <a href="{% url 'account_signup' %}?next={{ request.path }}" class="mt-4 inline-block bg-green-600 text-white px-4 py-2 rounded hover:bg-green-700 transition ml-2">{% trans "Sign Up" %}</a>
 
     </div>
+  {% elif not page.purchasable_products.exists %}
+    <div class="not-prose mt-8 p-4 bg-gray-100 border-l-4 border-gray-500 text-gray-700">
+      <p>{% trans "Course is not yet available for purchase. Please check back later." %}</p>
+    </div>
   {% else %}
     <div class="not-prose mt-8 p-4 bg-yellow-100 border-l-4 border-yellow-500 text-yellow-700">
       <p>{% trans "You don't have access to this course. Please purchase it to view the modules." %}</p>