Add comprehensive validation and error messages to the Seafile MySQL backup hook:
- Add timeout (5min) to prevent mysqldump from hanging indefinitely
- Validate SEAFILE_DB_PASSWORD is set before attempting dump
- Verify Docker container exists and is running before execution
- Fix file verification bug (check correct output filename)
- Add detailed logging for easier troubleshooting
- Use set -e for fail-fast behavior
Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>