- Added a new contacts database (`ContactsDB`) to store contact
information. This improves data organization and allows for
more efficient querying and manipulation of contact data.
- Implemented a virtual file system (VFS) for contacts
(`vfs_contacts`). This provides a file-like interface to access
and manage contact data, improving integration with existing
file-system-based tools and workflows. The VFS supports
listing by group, by name, and by email.
- Added model structs for contacts, improving data organization and
serialization. This lays the foundation for more robust data
handling and future expansion.