* pkg/debugdetect: add package for detecting debugger attachment
Implement new pkg/debugdetect package that detects if a program is
running under a debugger on Linux, macOS, Windows, and FreeBSD.
Platform-specific detection methods:
- Linux: Parse /proc/self/status for TracerPid field
- macOS: Use sysctl with KERN_PROC_PID to check P_TRACED flag
- Windows: Call IsDebuggerPresent() Win32 API
- FreeBSD: Try sysctl first, fall back to /proc/curproc/status
Fixes#4243
Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
