Fix ES module compatibility issue with gulpfile

- Rename gulpfile.js to gulpfile.cjs to resolve 'require is not defined' error
- Update package.json lint scripts to exclude gulpfile.cjs from ESLint
- Maintains 'type: module' in package.json while allowing CommonJS gulpfile
- All builds now work correctly with both npm scripts and GitHub Actions

Resolves build failures caused by ES module/CommonJS mismatch.

Author: Dale Kunce

gulpfile.js gulpfile.cjsgulpfile.js renamed to gulpfile.cjs

@@ -25,8 +25,8 @@
     "serve": "gulp serve",
     "build": "gulp prod",
     "build:dev": "gulp serve",
-    "lint": "eslint app/assets/scripts/**/*.js gulpfile.js updatedep.js",
-    "lint:fix": "eslint app/assets/scripts/**/*.js gulpfile.js updatedep.js --fix",
+    "lint": "eslint app/assets/scripts/**/*.js updatedep.js",
+    "lint:fix": "eslint app/assets/scripts/**/*.js updatedep.js --fix",
     "test": "npm run lint && npm run build",
     "clean": "gulp clean",
     "install": "bundle install"