✅ add prettier formatting check to CI workflow and npm scripts

- Add prettier job to GitHub Actions workflow to enforce code formatting
- Add format:check script to package.json for checking formatting
- Include failure message when prettier check fails in CI

package.json

@@ -51,6 +51,7 @@
     "deploy:patch": "npm version patch && npm run deploy:build",
     "lint": "eslint src --ext ts && tsc --noEmit",
     "format": "prettier --write src",
+    "format:check": "prettier --check src",
     "test": "node --no-warnings --experimental-vm-modules $( [ -f ./node_modules/.bin/jest ] && echo ./node_modules/.bin/jest || which jest ) test/unit",
     "test:all": "npm run test:unit:docker && npm run test:e2e:docker",
     "test:docker-build": "docker build -t oco-test -f test/Dockerfile .",