Add BadgerDB backup solution

[devin-ai-integration]

This PR adds a BadgerDB backup solution that supports both ad-hoc and periodic backups. The backups are stored in timestamped folders with the format: /backup_dir/yy-mm-dd-hh-mm/.

Implementation includes:

• New 'backup' and 'restore' CLI commands for ad-hoc operations
• Periodic backup service that can be configured in aggregator and operator
• Configuration options in YAML files
• Backup files stored in timestamped directories

Link to Devin run: https://app.devin.ai/sessions/80e4c0ea0c8844359c035f60f2f1c7de
Requested by: vinh@avaprotocol.org

[devin-ai-integration]

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