- Add sync task processing for both local and remote operations - Use
temp files for secure download operations - Update file metadata after
successful synchronization - Add proper error handling and cleanup for
sync operations - Display sync progress with appropriate status symbols

- Record vault state changes in sheet operations - Track modifications
when creating, dropping, or updating sheets - Mark vault as unmodified
after syncing with upstream - Add vault_modified module with check and
sign functions

Add comprehensive file update verification with detailed failure reasons including version mismatch, file not held, and missing descriptions.

The change from HashSet to Vec for task collections maintains the order
of file operations, which is important for consistent processing
behavior. This affects created_task, update_task, and sync_task
variables throughout the code.

- Implement SHA1 hash calculation module with async support
- Add file status analysis for tracking moves, creates, and modifications
- Enhance local file management with relative path handling
- Update virtual file actions with improved tracking capabilities

- Create virtual file actions module
- Add basic structure for virtual file operations
- NOTE: Still under development