feat(s3-backup-settings): add backup rotation to automatically delete old S3 backups

[Ahuahuachi]

Summary

Add a backup rotation feature to S3 Backup Settings that automatically deletes old backup folders from the S3 bucket after each successful upload, preventing unbounded storage growth.

Type of Change

• feat: New feature

Changes

• feat(s3-backup-settings): Add enable_backup_rotation and retention_count fields to the S3 Backup Settings DocType, allowing users to configure how many backup folders to keep.
• feat(s3-backup-settings): Implement delete_old_backups_from_s3() to list all backup folders in the S3 bucket, sort them by date (parsed from the YYYYMMDD_HHMMSS folder name), and delete the oldest folders that exceed the retention count.
• feat(s3-backup-settings): Add delete_s3_folder() helper to remove all objects within a given S3 folder prefix using paginated listing and batch delete_objects.
• feat(s3-backup-settings): Integrate rotation into the backup flow by calling delete_old_backups_from_s3() after each successful backup_to_s3().
• feat(s3-backup-settings): Add validation that retention_count is at least 1 when rotation is enabled.

Breaking Changes

None.

Related Issues

closes #19

Testing

• Verified that with rotation enabled, only the configured number of backup folders are retained after backup.
• Verified that rotation is skipped when disabled or retention_count is not set.
• Verified that folders with non-matching naming patterns are safely skipped.

[greptile-apps]

Confidence Score: 5/5

The rotation logic is sound and the previously identified gaps are addressed; safe to merge.

Path-prefix stripping, 1000-key delete batching, and error-logging are all correctly implemented. No remaining defects in the changed code paths.

No files require special attention.

_{Reviews (6): Last reviewed commit: "fix(s3-backup-settings): log rotation de..." | Re-trigger Greptile}