[agent-automation] Add Makefile and .gitignore for Go development

go.mod

@@ -0,0 +1,3 @@
+module github.com/marmaduke/testbed2
+
+go 1.24

main.go

@@ -0,0 +1,3 @@
+package main
+
+func main() {}

main_test.go

@@ -0,0 +1,7 @@
+package main
+
+import "testing"
+
+func TestModule(t *testing.T) {
+	// Basic test to verify module initialization
+}