Schedule daily DB backup (cron 2am) and gitignore backup files

- backup-db.sh tested successfully (19MB, pg_dump 17)
- Scheduled: 0 2 * * * with log to data/backups/backup.log
- Added data/backups/ and data/.auto-sync.log to .gitignore

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.gitignore

@@ -2,6 +2,8 @@ data/uploads/
 data/cases/
 data/training/
 data/exports/
+data/backups/
+data/.auto-sync.log
 mcp-server/.venv/
 __pycache__/
 *.pyc