ci: add validate-travis-macos.sh for issue #35 reviewers

Maintainers can run ./scripts/validate-travis-macos.sh locally to confirm
the macOS matrix is enabled and the failing Homebrew OpenCV path is gone.

Author: isaaclins

scripts/validate-travis-macos.sh

@@ -0,0 +1,27 @@
+#!/usr/bin/env bash
+# Validates .travis.yml for the macOS matrix fix (issue #35).
+# Run from repo root: ./scripts/validate-travis-macos.sh
+set -euo pipefail
+
+root="$(cd "$(dirname "$0")/.." && pwd)"
+cd "$root"
+
+echo "==> YAML parse"
+ruby -e 'require "yaml"; YAML.load_file(".travis.yml"); puts "yaml ok"'
+
+echo "==> macOS matrix entry enabled"
+grep -q '^[[:space:]]*- os: osx' .travis.yml || {
+  echo "FAIL: expected active '- os: osx' matrix entry"
+  exit 1
+}
+
+echo "==> macOS before_install skips Homebrew OpenCV"
+awk '/TRAVIS_OS_NAME.*osx/,/fi/ {print}' .travis.yml | grep -q 'brew install.*opencv' && {
+  echo "FAIL: macOS block still runs 'brew install ... opencv'"
+  exit 1
+} || true
+
+echo "==> whitespace"
+git diff --check
+
+echo "All checks passed."