Add a Job History section that loads past jobs via useQuery with:
- Animated skeleton placeholders while the job list is loading
- Error banner with retry button when the API call fails
- Empty state with helpful message when no jobs exist
- Job list cards with status badges and progress bars
Also improve the batch submission error state with a retry button
alongside the existing dismiss button.
Closesleeworks-agents/SPARC#343
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>