feat: Sandbox implementation with seatbelt

sandbox/sandbox_unsupported.go

@@ -0,0 +1,11 @@
+//go:build !darwin && !linux && !windows
+// +build !darwin,!linux,!windows
+
+package sandbox
+
+import "fmt"
+
+// newPlatformSandbox returns an error on unsupported platforms.
+func newPlatformSandbox() (Sandbox, error) {
+	return nil, fmt.Errorf("sandbox is not supported on this platform")
+}