Keep the CLI working when the disk fails

A single unreadable block on a station's disk used to stop every TofuPilot command, including the update that would have fixed it.

• Fixed a damaged local state file stopping the CLI entirely. It is now set aside automatically and rebuilt, and the station stays logged in because credentials are stored separately.
• Added the operating system's own error name and one concrete action to filesystem failures during a pull, so a full disk or a damaged volume names itself instead of looking like a TofuPilot bug.
• Improved the recovery warning, which now points to the copy of the damaged file kept on disk for support.