Add ESLint config and Node.js test suite (198/198 passing)

package.json

@@ -0,0 +1,16 @@
+{
+  "name": "sorting-visualization",
+  "version": "1.0.0",
+  "description": "Sorting algorithm visualization - single-file HTML app",
+  "private": true,
+  "scripts": {
+    "lint": "eslint sorting_visualization.html",
+    "test": "node test_algorithms.js",
+    "test:verbose": "node test_algorithms.js --verbose"
+  },
+  "devDependencies": {
+    "eslint": "^9.0.0",
+    "@eslint/js": "^9.0.0",
+    "globals": "^16.0.0"
+  }
+}