fix: add FreeBSD and OpenBSD platform support

Add capabilities_bsd.go for terminal handling on BSD systems.
Add sysinfo_bsd.go stub for CPU monitoring on BSD systems.

Author: Gaurav-Gosain

internal/app/capabilities_bsd.go

@@ -0,0 +1,77 @@
+//go:build freebsd || openbsd
+
+package app
+
+import (
+	"time"
+
+	"golang.org/x/sys/unix"
+)
+
+func isTerminal(fd uintptr) bool {
+	_, err := unix.IoctlGetTermios(int(fd), unix.TIOCGETA)
+	return err == nil
+}
+
+func makeRaw(fd uintptr) (*unix.Termios, error) {
+	termios, err := unix.IoctlGetTermios(int(fd), unix.TIOCGETA)
+	if err != nil {
+		return nil, err
+	}
+
+	oldState := *termios
+
+	termios.Iflag &^= unix.IGNBRK | unix.BRKINT | unix.PARMRK | unix.ISTRIP | unix.INLCR | unix.IGNCR | unix.ICRNL | unix.IXON
+	termios.Oflag &^= unix.OPOST
+	termios.Lflag &^= unix.ECHO | unix.ECHONL | unix.ICANON | unix.ISIG | unix.IEXTEN
+	termios.Cflag &^= unix.CSIZE | unix.PARENB
+	termios.Cflag |= unix.CS8
+	termios.Cc[unix.VMIN] = 1
+	termios.Cc[unix.VTIME] = 0
+
+	if err := unix.IoctlSetTermios(int(fd), unix.TIOCSETA, termios); err != nil {
+		return nil, err
+	}
+
+	return &oldState, nil
+}
+
+func restoreTerminal(fd uintptr, oldState *unix.Termios) {
+	if oldState != nil {
+		_ = unix.IoctlSetTermios(int(fd), unix.TIOCSETA, oldState)
+	}
+}
+
+// queryTerminalSize gets the terminal columns and rows using TIOCGWINSZ
+func queryTerminalSize(caps *HostCapabilities) {
+	ws, err := unix.IoctlGetWinsize(int(unix.Stdout), unix.TIOCGWINSZ)
+	if err != nil {
+		return
+	}
+	caps.Cols = int(ws.Col)
+	caps.Rows = int(ws.Row)
+	// Also get pixel dimensions if available
+	if ws.Xpixel > 0 && caps.PixelWidth == 0 {
+		caps.PixelWidth = int(ws.Xpixel)
+	}
+	if ws.Ypixel > 0 && caps.PixelHeight == 0 {
+		caps.PixelHeight = int(ws.Ypixel)
+	}
+}
+
+// pollReadable uses poll to wait for the file descriptor to be readable with a timeout
+func pollReadable(fd uintptr, timeout time.Duration) (bool, error) {
+	fds := []unix.PollFd{
+		{Fd: int32(fd), Events: unix.POLLIN},
+	}
+	timeoutMs := int(timeout.Milliseconds())
+	if timeoutMs < 1 {
+		timeoutMs = 1
+	}
+
+	n, err := unix.Poll(fds, timeoutMs)
+	if err != nil {
+		return false, err
+	}
+	return n > 0 && (fds[0].Revents&unix.POLLIN) != 0, nil
+}

internal/system/sysinfo_bsd.go

@@ -0,0 +1,10 @@
+//go:build freebsd || openbsd
+
+package system
+
+// readCPUUsage returns the CPU usage on BSD systems.
+// Currently returns 0 as BSD CPU usage monitoring is not implemented.
+func (c *CPUMonitor) readCPUUsage() (float64, error) {
+	// TODO: Implement BSD CPU monitoring using sysctl
+	return 0, nil
+}