Add local fix script and codex validation guidance

scripts/fix.sh

@@ -0,0 +1,20 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+echo "[fix] formatting Go files"
+files="$(git ls-files '*.go')"
+if [[ -n "${files}" ]]; then
+  gofmt -w ${files}
+fi
+
+echo "[fix] running go mod tidy"
+go mod tidy
+
+if command -v terraform >/dev/null 2>&1; then
+  echo "[fix] running terraform fmt for examples/"
+  terraform fmt -recursive examples
+else
+  echo "[fix][warn] terraform not found; skipping examples/ formatting" >&2
+fi
+
+echo "[fix] complete"