Enable ESLint no-undef rule (#4346)

# Description of Changes
Enable ESLint [no-undef
rule](https://eslint.org/docs/latest/rules/no-undef)

frontend/eslint.config.mjs

@@ -1,9 +1,18 @@
 // @ts-check
 
 import eslint from '@eslint/js';
+import globals from "globals";
 import { defineConfig } from 'eslint/config';
 import tseslint from 'typescript-eslint';
 
+const srcGlobs = [
+  'src/**/*.{js,mjs,jsx,ts,tsx}',
+];
+const nodeGlobs = [
+  'scripts/**/*.{js,ts,mjs}',
+  '*.config.{js,ts,mjs}',
+];
+
 export default defineConfig(
   eslint.configs.recommended,
   tseslint.configs.recommended,
@@ -15,7 +24,6 @@ export default defineConfig(
   },
   {
     rules: {
-      "no-undef": "off", // Temporarily disabled until codebase conformant
       "@typescript-eslint/no-empty-object-type": [
         "error",
         {
@@ -38,5 +46,23 @@ export default defineConfig(
         },
       ],
     },
-  }
+  },
+  // Config for browser scripts
+  {
+    files: srcGlobs,
+    languageOptions: {
+      globals: {
+        ...globals.browser,
+      }
+    }
+  },
+  // Config for node scripts
+  {
+    files: nodeGlobs,
+    languageOptions: {
+      globals: {
+        ...globals.node,
+      }
+    }
+  },
 );

frontend/package-lock.json

@@ -41,6 +41,7 @@
         "@tanstack/react-virtual": "^3.13.12",
         "autoprefixer": "^10.4.21",
         "axios": "^1.12.2",
+        "globals": "^16.4.0",
         "i18next": "^25.5.2",
         "i18next-browser-languagedetector": "^8.2.0",
         "i18next-http-backend": "^3.0.2",
@@ -1760,6 +1761,19 @@
         "mlly": "^1.7.4"
       }
     },
+    "node_modules/@iconify/utils/node_modules/globals": {
+      "version": "15.15.0",
+      "resolved": "https://registry.npmjs.org/globals/-/globals-15.15.0.tgz",
+      "integrity": "sha512-7ACyT3wmyp3I61S4fG682L0VA2RGD9otkqGJIwNUMF1SWUombIIk+af1unuDYgMm082aHYwD+mzJvv9Iu8dsgg==",
+      "dev": true,
+      "license": "MIT",
+      "engines": {
+        "node": ">=18"
+      },
+      "funding": {
+        "url": "https://github.com/sponsors/sindresorhus"
+      }
+    },
     "node_modules/@isaacs/cliui": {
       "version": "8.0.2",
       "resolved": "https://registry.npmjs.org/@isaacs/cliui/-/cliui-8.0.2.tgz",
@@ -6415,10 +6429,9 @@
       }
     },
     "node_modules/globals": {
-      "version": "15.15.0",
-      "resolved": "https://registry.npmjs.org/globals/-/globals-15.15.0.tgz",
-      "integrity": "sha512-7ACyT3wmyp3I61S4fG682L0VA2RGD9otkqGJIwNUMF1SWUombIIk+af1unuDYgMm082aHYwD+mzJvv9Iu8dsgg==",
-      "dev": true,
+      "version": "16.4.0",
+      "resolved": "https://registry.npmjs.org/globals/-/globals-16.4.0.tgz",
+      "integrity": "sha512-ob/2LcVVaVGCYN+r14cnwnoDPUufjiYgSqRhiFD0Q1iI4Odora5RE8Iv1D24hAz5oMophRGkGz+yuvQmmUMnMw==",
       "license": "MIT",
       "engines": {
         "node": ">=18"

frontend/package.json

@@ -37,6 +37,7 @@
     "@tanstack/react-virtual": "^3.13.12",
     "autoprefixer": "^10.4.21",
     "axios": "^1.12.2",
+    "globals": "^16.4.0",
     "i18next": "^25.5.2",
     "i18next-browser-languagedetector": "^8.2.0",
     "i18next-http-backend": "^3.0.2",