New Feature
1- Auto-download backup file automatically upon completion
Improvement
1- Refactor backup/restore modal to use non-blocking BackgroundJobs toast notifications (bottom-right progress, page remains interactive)
Bug Fixes
2- Fix out-of-memory crash when downloading large backup files by replacing fetch().blob() with direct browser streaming via anchor tag
- Fix null-safe array access for stack volumes (stack.volumes || []) to prevent render crash