agent-guard: Making Destructive AI Operations Reversible by Default

`agent-guard` is a DeepSeek Harness plugin designed to improve the reliability of AI agents when executing Shell commands and prevent data loss caused by mistakes. Its core value is making destructive operations reversible by default. The plugin provides capabilities such as isolated deletion (redirecting deletions to the Trash), Git snapshots, human confirmation (ASK), and audit logs. It is not intended to function as a security sandbox; instead, it guards against operational mistakes and is suitable for scenarios where agents need to autonomously clean up a workspace.