b0816502bf
- Add image_prune_threshold_mb setting (default 1024 MB) - Add GET /api/docker/unused-images endpoint returning unused image count, size, and threshold status - Dashboard shows amber warning banner when unused project images exceed threshold - Banner links to settings page for pruning, shows count and human-readable size (MB/GB) - Threshold configurable in Docker Image Cleanup section of settings - DB migration + schema for image_prune_threshold_mb