Redesign jobs dashboard with unified table and progress bar

- Add overall progress bar showing completed/active/failed counts
- Unify all job types into single table with Type column
- Simplify status to Working/Pending/Failed badges
- Remove NPM "Coming Soon" section
- Add get_recent_activity() function for future activity feed
- Fix dark mode CSS using CSS variables

backend/app/pypi_proxy.py

@@ -29,6 +29,7 @@ from .pypi_cache_worker import (
     get_cache_status,
     get_failed_tasks,
     get_active_tasks,
+    get_recent_activity,
     retry_failed_task,
     retry_all_failed_tasks,
 )