Merge pull request 'Initialize Go module (go.mod)' (#8) from feature/init-go-module into main

go.mod

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

main.go

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+package main
+
+func main() {}

main_test.go

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+package main
+
+import "testing"
+
+func TestModule(t *testing.T) {
+	// Basic test to verify module initialization
+}