[BUG] Standalone CLI binary missing seccomp binaries — /doctor reports "seccomp not available"

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

The standalone CLI binary does not bundle the apply-seccomp binaries or BPF filters from @anthropic-ai/sandbox-runtime. As a result, /doctor reports:

Sandbox
└ Status: Available (with warnings)
└ seccomp not available - unix socket access not restricted

The same seccomp binaries are present in the VS Code extension bundle:

/snap/code/226/usr/share/code/resources/app/node_modules/@anthropic-ai/sandbox-runtime/dist/vendor/seccomp/x64/apply-seccomp
/snap/code/226/usr/share/code/resources/app/node_modules/@anthropic-ai/sandbox-runtime/vendor/seccomp/x64/apply-seccomp

But the standalone CLI at ~/.local/share/claude/versions/2.1.56 is a single ELF binary with no companion files — no vendor/seccomp/ directory exists anywhere in the CLI installation.

What Should Happen?

The standalone CLI should bundle the seccomp binaries so that unix socket access is restricted, matching the security posture of the VS Code extension.

Error Messages/Logs

$ claude /doctor
Sandbox
└ Status: Available (with warnings)
└ seccomp not available - unix socket access not restricted

Steps to Reproduce

1. Install Claude Code CLI (claude standalone binary, not via VS Code)
2. Run /doctor
3. Observe seccomp warning

Claude Model

N/A

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.56

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux (kernel 6.17.0, x86_64)

Terminal/Shell

zsh

Additional Information

This is distinct from #12007 / #11874 which are about the VS Code extension crashing due to seccomp debug messages being written to stdout. This issue is specifically about the standalone CLI not including the seccomp binaries at all.