Deprecated: sandbox image moved to the launcher repo

The Dockerfile + entrypoint + helper scripts in this directory have been copied to the launcher repository at launcher/sandbox-image/. The launcher is now the source of truth for the devbox sandbox image under the v22 cut (Shape B — agent runs on the host, container is a generic dev environment driven via SandboxSession).

These files are kept here temporarily for backward compatibility with:

• Existing omni sandbox --dockerfile <path> invocations
• The published ghcr.io/ericmichael/omni-code-sandbox-work:latest tag that the launcher's bundled devbox.yml profile still references

Once the launcher CI publishes images from launcher/sandbox-image/ and devbox.yml points at the launcher-published tag, this directory and the omni sandbox CLI subcommand can be removed entirely.

Until then, edit the launcher copy, not this one — keeping the two in lockstep is not worth the friction.