refactor(js): move media.js to CMS module

Media library management is part of content management (CMS).
This matches the Python pattern where:
- Core media service (upload, storage) stays in platform
- Media library UI (browsing, organizing) goes to CMS module
- Media picker component stays shared (used by products, CMS, etc.)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/templates/vendor/media.html

@@ -441,5 +441,5 @@
 {% endblock %}
 
 {% block extra_scripts %}
-<script src="{{ url_for('static', path='vendor/js/media.js') }}"></script>
+<script src="{{ url_for('cms_static', path='vendor/js/media.js') }}"></script>
 {% endblock %}