tools: add helper to check go mod tidy changes

Added a script that checks whether go mod tidy results in module changes.

devtools/check_go_mod_tidy.sh

@@ -0,0 +1,40 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# Helper script to check whether `go mod tidy` introduces changes.
+
+ROOT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+cd "${ROOT_DIR}"
+
+if [ ! -f go.mod ]; then
+  echo "go.mod not found in repository root."
+  exit 1
+fi
+
+echo "Running go mod tidy (dry check)..."
+
+# Save a snapshot of go.mod and go.sum
+cp go.mod /tmp/go.mod.before
+cp go.sum /tmp/go.sum.before
+
+go mod tidy
+
+changed=
+if ! diff -q go.mod /tmp/go.mod.before >/dev/null 2>&1; then
+  changed=1
+fi
+
+if ! diff -q go.sum /tmp/go.sum.before >/dev/null 2>&1; then
+  changed=1
+fi
+
+if [ -n "${changed}" ]; then
+  echo "⚠️  go mod tidy introduced changes."
+  echo "Please review and commit them if appropriate."
+else
+  echo "✅ go mod tidy did not change go.mod or go.sum."
+fi
+
+# Restore original files to avoid modifying the working tree.
+mv /tmp/go.mod.before go.mod
+mv /tmp/go.sum.before go.sum