Add Husky + lint-staged + ESLint with CI enforcement

.editorconfig

@@ -0,0 +1,8 @@
+root = true
+
+[*]
+end_of_line = lf
+insert_final_newline = true
+charset = utf-8
+indent_style = space
+indent_size = 2

.github/workflows/ci.yml

@@ -2,7 +2,7 @@ name: CI
 
 on:
   push:
-    branches: ['**']
+    branches: ['**'] # run on pushes to all branches
     paths:
       - 'src/**'
       - 'plugins/**'
@@ -13,28 +13,24 @@ on:
       - 'vitest.config.js'
       - '.github/workflows/**'
   pull_request:
-    branches: ['**']
+    branches: ['**'] # run on PRs against any branch
 
 concurrency:
   group: ci-${{ github.ref }}
   cancel-in-progress: true
 
 jobs:
-  # Primary job: use webpack build (stable), then test with coverage.
+  # Primary job: format/lint, webpack build, then tests with coverage.
   build-and-test:
     runs-on: ubuntu-24.04
-    strategy:
-      fail-fast: false
-      matrix:
-        node-version: [22.x] # stick to Node 22 LTS for CI stability
     steps:
       - name: Checkout
         uses: actions/checkout@v4
 
-      - name: Setup Node.js ${{ matrix.node-version }}
+      - name: Setup Node.js (from .nvmrc)
         uses: actions/setup-node@v4
         with:
-          node-version: ${{ matrix.node-version }}
+          node-version-file: .nvmrc
           cache: npm
 
       - name: Install dependencies
@@ -45,9 +41,12 @@ jobs:
             npm install
           fi
 
-      - name: Check formatting
+      - name: Prettier check
         run: npm run format-check
 
+      - name: ESLint
+        run: npm run lint
+
       # Use the webpack build for CI stability (dist via webpack)
       - name: Build (webpack)
         run: npm run build
@@ -61,7 +60,7 @@ jobs:
         if: always()
         uses: actions/upload-artifact@v4
         with:
-          name: coverage-${{ matrix.node-version }}
+          name: coverage
           path: coverage
           if-no-files-found: ignore
 
@@ -74,10 +73,10 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v4
 
-      - name: Setup Node.js 22
+      - name: Setup Node.js (from .nvmrc)
         uses: actions/setup-node@v4
         with:
-          node-version: 22.x
+          node-version-file: .nvmrc
           cache: npm
 
       - name: Install dependencies

.gitignore

@@ -1,4 +1,5 @@
 node_modules
 dist
 .idea/
-coverage/
+coverage/
+.eslintcache

.husky/pre-commit

@@ -0,0 +1,2 @@
+# Only format and lint what's staged (fast)
+npx lint-staged

.nvmrc

@@ -0,0 +1 @@
+v22.21.1

eslint.config.js

@@ -0,0 +1,69 @@
+import js from '@eslint/js';
+import prettier from 'eslint-config-prettier';
+
+export default [
+  {
+    ignores: ['dist/', 'node_modules/', 'coverage/', 'types/'],
+  },
+  js.configs.recommended,
+  prettier,
+  {
+    languageOptions: {
+      ecmaVersion: 2022,
+      sourceType: 'module',
+      globals: {
+        // Browser globals
+        window: 'readonly',
+        document: 'readonly',
+        navigator: 'readonly',
+        console: 'readonly',
+        alert: 'readonly',
+        HTMLElement: 'readonly',
+        HTMLVideoElement: 'readonly',
+        HTMLCanvasElement: 'readonly',
+        Image: 'readonly',
+        ImageData: 'readonly',
+        fetch: 'readonly',
+        CustomEvent: 'readonly',
+        MediaStream: 'readonly',
+        performance: 'readonly',
+        screen: 'readonly',
+        location: 'readonly',
+        WebAssembly: 'readonly',
+        setTimeout: 'readonly',
+        clearTimeout: 'readonly',
+        setInterval: 'readonly',
+        clearInterval: 'readonly',
+        requestAnimationFrame: 'readonly',
+        cancelAnimationFrame: 'readonly',
+        // Node.js globals
+        process: 'readonly',
+        __dirname: 'readonly',
+        __filename: 'readonly',
+        require: 'readonly',
+        module: 'readonly',
+        exports: 'readonly',
+        // Testing globals (vitest)
+        describe: 'readonly',
+        test: 'readonly',
+        it: 'readonly',
+        expect: 'readonly',
+        beforeEach: 'readonly',
+        afterEach: 'readonly',
+        beforeAll: 'readonly',
+        afterAll: 'readonly',
+        vi: 'readonly',
+        // AR.js specific globals
+        ArToolkitContext: 'writable',
+        ArMarkerControls: 'writable',
+      },
+    },
+    rules: {
+      // Relax rules for existing codebase patterns
+      'no-empty': 'off',
+      'no-unused-vars': 'off',
+      'no-unused-private-class-members': 'off',
+      'no-redeclare': 'off',
+    },
+  },
+];