GHSA-9f72-qcpw-2hxc: OpenClaw: Native prompt image auto-load did not honor tools.fs.workspaceOnly in sandboxed runs

In sandboxed runs, native prompt image auto-load did not honor tools.fs.workspaceOnly=true.

This optional hardening setting is not enabled by default. When operators enabled it, prompt text could still reference mounted out-of-workspace image paths (for example /agent/secret.png) and load those image bytes for vision-capable model input.