Add cross-platform support for type builtin

[coderabbitai]

Context

The type builtin currently uses Unix-specific code that won't compile on Windows:

• std::os::unix::fs::PermissionsExt trait (line 5 in src/main.rs)
• PATH separator ":" is Unix-specific (Windows uses ";")

Suggested approach

Consider using conditional compilation with #[cfg(unix)] and #[cfg(windows)] attributes to support both platforms, or document that the shell is Unix-only.

References

• PR: feat(type): extend type builtin to search for executables #5
• Comment: feat(type): extend type builtin to search for executables #5 (comment)
• Requested by: @Pawank06