suggestion: local, periodic backup option (KBFS, chats)

A blocking issue in adopting Keybase for organizations with legal requirements to implement data retention policies (e.g. law firms, medical clinics) is that no convenient, automated local backup function is available. Technical users/orgs can of course rsync their keybase filesystem (KBFS) folders to a local disk, but this isn't enough to convince non-technical organizations without internal IT support.

A related issue is the inability to export or backup chats. This might be less of an issue if chats are all stored locally on devices, but KBFS files are only reliable accessible if keybase servers are available.

Any suggestions? Could a backup option be implemented in the client?

(related to resilience issue #3089)

Start by reviewing the requested local backup behavior for KBFS and chats, along with related issue #3089. No files, tests, or entry points are identified; define the backup scope and retention requirements before implementation, with automated local backups for both data types as the completion target.

Written by the indexing model from the issue text.