Sync Status Dashboard (Local) and manual control

[dmitrytrager]

Display sync status in Clinical Edge admin UI

• Show current sync status with progress bar
• Display manifest versions: current vs latest <---- we may have difference only before sync process
• Show last successful sync timestamp
• Display content summary:
  • Providers count: ContentProvider.count
  • Topics count: Topic.count
  • Files count: TopicFile.count
  • Total size: TopicFile.sum(:file_size)
• Show ActiveStorage disk usage: ActiveStorage::Blob.sum(:byte_size)

UI controls for sync operations

• "Check for Updates" button → triggers ManifestChecker
• "Sync Now" button → enqueues ContentSyncJob
• "Cancel Sync" button → sets cancellation flag, job checks and aborts <----- could be a separate task
• Display sync log/history from SyncProgress records