Module update 

Update command implementations (add, remove, modify, compact)

These commands enable incremental modifications to existing engrams without full re-ingestion.

Functions

handle_update_add

Add a new file to an existing engram

handle_update_compact

Compact the engram by rebuilding without deleted files

handle_update_modify

Modify an existing file in the engram

handle_update_remove

Remove a file from the engram (mark as deleted)