test: add Jest configuration and fix test path resolution

- Add jest.config.js with proper Node.js environment configuration
- Fix train.test.js to use correct relative path: '../../js/train.js'
- Add module.exports to train.js for Node.js module loading
- Update package.json with proper test scripts (test:unit, test:e2e, test:coverage)

package.json

@@ -1,20 +1,27 @@
 {
   "name": "railtrack_pro",
   "version": "1.0.0",
-  "description": "**A web-based railway construction game featuring track building, junctions, signals, and 3D driver's eye view.**",
-  "main": "index.js",
+  "description": "A web-based railway construction game featuring track building, junctions, signals, and 3D driver's eye view.",
   "directories": {
     "test": "test"
   },
   "scripts": {
-    "test": "echo \"Error: no test specified\" && exit 1"
+    "start": "python3 -m http.server 8080",
+    "test": "npm run test:unit",
+    "test:unit": "jest",
+    "test:e2e": "playwright test",
+    "test:all": "npm run test:unit && npm run test:e2e",
+    "test:coverage": "jest --coverage",
+    "test:watch": "jest --watch",
+    "test:report": "jest --coverage --coverageReporters=html"
   },
-  "keywords": [],
-  "author": "",
+  "keywords": ["game", "railway", "threejs"],
+  "author": "Railtrack Pro Team",
   "license": "ISC",
   "devDependencies": {
     "@playwright/test": "^1.58.2",
     "jest": "^30.3.0",
+    "jest-environment-jsdom": "^29.7.0",
     "jsdom": "^28.1.0"
   }
 }