Unreviewed file writes via tool-only approval caching

Incorrect authorization in PraisonAI before 1.6.78 allows attackers to reuse a benign tool approval for arbitrary file writes. ApprovalRegistry.is_already_approved keys its per-run cache only by tool name, and approve_sync and approve_async bypass the approval backend on a cache hit. Exploitation requires a user to approve an initial benign call; malicious input steering the same session can then cause later write_file calls to overwrite sensitive files without another prompt.