fix: detect macOS ACL support using uname instead of chmod output

[alies-dev]

Problem

When deploy:writable runs in acl mode, the code detects macOS ACL support by running:

run("chmod 2>&1; true")

This outputs an error message to the deployment logs:

chmod: missing operand
Try 'chmod --help' for more information.

While the command succeeds (due to ; true), the error message clutters deployment output.

Solution

Since chmod +a is macOS-specific (Linux and FreeBSD use setfacl/getfacl instead), we can directly check the OS:

run("uname -s") === 'Darwin'

This is:

• Cleaner: No error output in logs
• More explicit: Clearly documents the intent (macOS detection)
• Equally reliable: macOS is the only platform supporting chmod +a

References

• macOS uses chmod +a/-a/=a for ACL management
• Linux uses setfacl/getfacl (POSIX ACLs)
• FreeBSD uses setfacl/getfacl despite being BSD-based