[Bug] Sandbox mode unavailable on macOS - missing platform support

Bug Description
I can't enable /sandbox mode on macos. the options are for linux and there's no interaction to enable it.

!Image

Environment Info

• Platform: darwin
• Terminal: iTerm.app
• Version: 2.1.71
• Feedback ID: bb8399bf-4fa1-4f1f-8502-2a8729c796dd
• Chip: Apple M3 Pro
• OS: tahoe 26.3.1

Errors

[{"error":"Error: NON-FATAL: Lock acquisition failed for /Users/REDACTED/.local/share/claude/versions/2.1.71 (expected in multi-process scenarios)\n    at Xxq (/$bunfs/root/src/entrypoints/cli.js:2603:2066)\n    at zU8 (/$bunfs/root/src/entrypoints/cli.js:2603:1210)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-03-07T04:52:51.258Z"}]