fix: sort import jobs by newest first and fix language parameter

Sorting:
- Add id DESC as tiebreaker when created_at timestamps are equal
- Ensures consistent newest-first ordering on imports and marketplace pages

Language bug fix:
- Add language field to startImport() payload in marketplace.js
- Add language column to MarketplaceImportJob database model
- Store and return language in API responses
- Add cache-busting version parameter to script tag

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

app/templates/admin/marketplace.html

@@ -347,5 +347,5 @@
 {% endblock %}
 
 {% block extra_scripts %}
-<script src="{{ url_for('static', path='admin/js/marketplace.js') }}"></script>
+<script src="{{ url_for('static', path='admin/js/marketplace.js') }}?v=2"></script>
 {% endblock %}