[Feature Request] Implementation of Mirror Sync (Deletion Propagation) for Mobile and App

[arturohrv]

Problem:
The current backup system is strictly incremental. Deleted files at the source remain in the destination, causing data clutter and preventing efficient storage management for users who require a 1:1 replica of their data.

Proposed Solution:
Integrate an optional "Mirror Sync" mode across the ZimaOS ecosystem to support deletion propagation:

• ZimaOS Mobile App: Option to sync mobile folders where deleting a file on the phone automatically removes it from the NAS.
• ZimaOS Backup App: A toggle in the backup tasks to ensure that any file removed from the source folder is also deleted from the destination (External Drive/Remote Storage).

Key Benefits:

• Storage Efficiency: Prevents the accumulation of redundant data.
• Workflow Consistency: Ensures that organized libraries (Photos/Documents) are identical across all devices and backups.
• User Choice: This should be an optional toggle per task to avoid accidental data loss for users who prefer traditional incremental backups.

Alternatives Considered:
Manual cleanup or using CLI tools like rsync --delete, which lack the integrated GUI experience of ZimaOS.