feat(debug): add interactive ptrace debugger MVP — single-step, regs, breakpoints, labels

Assisted-by: Qwen 3.8 Max Preview

cmd/gasm/debug_other.go

@@ -0,0 +1,16 @@
+// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
+// SPDX-License-Identifier: BSD-3-Clause
+
+//go:build !(linux && amd64)
+
+package main
+
+import (
+	"fmt"
+	"os"
+)
+
+func cmdDebug(args []string) int {
+	fmt.Fprintln(os.Stderr, "gasm debug: the interactive debugger requires linux/amd64 (ptrace)")
+	return 1
+}