feat: Go project scaffolding - module init, directory structure, CLI skeleton, Makefile, CI

Co-authored-by: multica-agent <github@multica.ai>

cmd/exploredns/main.go

@@ -0,0 +1,26 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"os"
+)
+
+func main() {
+	flag.Usage = func() {
+		fmt.Fprintf(os.Stderr, "ExploreDNS - DNS reconnaissance and exploration tool\n\n")
+		fmt.Fprintf(os.Stderr, "Usage:\n")
+		fmt.Fprintf(os.Stderr, "  exploredns [flags] <domain>\n\n")
+		fmt.Fprintf(os.Stderr, "Flags:\n")
+		flag.PrintDefaults()
+	}
+
+	flag.Parse()
+
+	if flag.NArg() == 0 {
+		flag.Usage()
+		os.Exit(1)
+	}
+
+	fmt.Printf("ExploreDNS - exploring: %s\n", flag.Arg(0))
+}